Technique for configuring preamble in wireless communication system

ABSTRACT

An example according to the present specification relates to a technique relating to a configuration of a preamble in a wireless LAN (WLAN) system. A reception STA can receive a PPDU. The reception STA can perform a modulo operation with respect to whether or not an L-SIG field is repeated and a value of a length field. The reception STA can determine the received PPDU as an EHT PPDU on the basis of the modulo operation with respect to whether or not the L-SIG field is repeated and the value of the length field.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.17/623,800, filed on Dec. 29, 2021, which is a National Stage filingunder 35 U.S.C. § 371 of International Application No.PCT/KR2020/008608, filed on Jul. 1, 2020, and claims priority to and thebenefit of Korean Application No. 10-2019-0080946, filed on Jul. 4,2019, all of which are incorporated by reference in their entiretyherein.

BACKGROUND Technical Field

The present specification relates to a technique for configuring apreamble in a wireless local area network (WLAN) system and, moreparticularly, to a method for configuring a preamble in a WLAN systemand an apparatus for supporting the same.

Related Art

A wireless local area network (WLAN) has been enhanced in various ways.For example, the IEEE 802.11ax standard has proposed an enhancedcommunication environment by using orthogonal frequency divisionmultiple access (OFDMA) and downlink multi-user multiple input multipleoutput (DL MU MIMO) schemes.

The present specification proposes a technical feature that can beutilized in a new communication standard. For example, the newcommunication standard may be an extreme high throughput (EHT) standardwhich is currently being discussed. The EHT standard may use anincreased bandwidth, an enhanced PHY layer protocol data unit (PPDU)structure, an enhanced sequence, a hybrid automatic repeat request(HARQ) scheme, or the like, which is newly proposed. The EHT standardmay be called the IEEE 802.11be standard.

SUMMARY

In an EHT standard, a wide bandwidth (i.e., 160/320 MHz) and 16 streamsmay be used to support high throughput. Further, when a PPDU based onthe EHT standard (e.g., an EHT PPDU) is transmitted, backwardcompatibility with a device according to a legacy standard (e.g., aconventional Wi-Fi device) may be supported. Therefore, there may berequired a method for reducing packet detection errors with respect to aPPDU (or packet) based on the EHT standard.

A receiving STA according to various embodiments may receive a physicalprotocol data unit (PPDU) including an L-SIG field.

According to various embodiments, the receiving STA may determine thetype of the PPDU based on whether the L-SIG field is repeated and a“modulo 3 operation” with respect to the value of a length field.

According to various embodiments, the type of the PPDU may be determinedas an extreme high throughput (EHT) type for a PPDU in which the resultof the “modulo 3 operation” is “0”.

According to various embodiments, the PPDU of the EHT type may includean RL-SIG field in which the L-SIG field is repeated.

According to various embodiments, the receiving STA may decode the PPDU.

According to various embodiments, a receiving STA may determine the typeof a PPDU based on whether an L-SIG field is repeated and a modulooperation with respect to the value of a length field. The PPDU may beconfigured in a different structure for each type. Therefore, thereceiving STA may identify whether the L-SIG field is repeated and mayperform the modulo operation with respect to the value of the lengthfield in order to identify a PPDU in an EHT format.

Therefore, according to various embodiments, it is possible to reducepacket detection errors by the receiving STA. Further, the EHT PPDUincludes the L-SIG field, thus supporting backward compatibility with aconventional Wi-Fi device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a transmitting apparatus and/orreceiving apparatus of the present specification.

FIG. 2 is a conceptual view illustrating the structure of a wirelesslocal area network (WLAN).

FIG. 3 illustrates a general link setup process.

FIG. 4 illustrates an example of a PPDU used in an IEEE standard.

FIG. 5 illustrates a layout of resource units (RUs) used in a band of 20MHz.

FIG. 6 illustrates a layout of RUs used in a band of 40 MHz.

FIG. 7 illustrates a layout of RUs used in a band of 80 MHz.

FIG. 8 illustrates the structure of an HE-SIG-B field.

FIG. 9 illustrates an example in which a plurality of user STAs isallocated to the same RU through a MU-MIMO scheme.

FIG. 10 illustrates an operation based on UL-MU.

FIG. 11 illustrates an example of a trigger frame.

FIG. 12 illustrates an example of a common information field of atrigger frame.

FIG. 13 illustrates an example of a subfield included in a per userinformation field.

FIG. 14 illustrates a technical feature of a UORA scheme.

FIG. 15 illustrates an example of a channel used/supported/definedwithin a 2.4 GHz band.

FIG. 16 illustrates an example of a channel used/supported/definedwithin a 5 GHz band.

FIG. 17 illustrates an example of a channel used/supported/definedwithin a 6 GHz band.

FIG. 18 illustrates an example of a PPDU used in the presentspecification.

FIG. 19 illustrates an example of a modified transmitting apparatusand/or receiving apparatus of the present specification.

FIG. 20 illustrates a format of an EHT PPDU.

FIG. 21 illustrates another format of an EHT PPDU.

FIG. 22 illustrates another format of an EHT PPDU.

FIG. 23 illustrates another format of an EHT PPDU.

FIG. 24 is a flowchart illustrating an embodiment of an operation of atransmitting STA.

FIG. 25 is a flowchart illustrating an embodiment of an operation of areceiving STA.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

In the present specification, “A or B” may mean “only A”, “only B” or“both A and B”. In other words, in the present specification, “A or B”may be interpreted as “A and/or B”. For example, in the presentspecification, “A, B, or C” may mean “only A”, “only B”, “only C”, or“any combination of A, B, C”.

A slash (/) or comma used in the present specification may mean“and/or”. For example, “A/B” may mean “A and/or B”. Accordingly, “A/B”may mean “only A”, “only B”, or “both A and B”. For example, “A, B, C”may mean “A, B, or C”.

In the present specification, “at least one of A and B” may mean “onlyA”, “only B”, or “both A and B”. In addition, in the presentspecification, the expression “at least one of A or B” or “at least oneof A and/or B” may be interpreted as “at least one of A and B”.

In addition, in the present specification, “at least one of A, B, and C”may mean “only A”, “only B”, “only C”, or “any combination of A, B, andC”. In addition, “at least one of A, B, or C” or “at least one of A, B,and/or C” may mean “at least one of A, B, and C”.

In addition, a parenthesis used in the present specification may mean“for example”. Specifically, when indicated as “control information(EHT-signal)”, it may mean that “EHT-signal” is proposed as an exampleof the “control information”. In other words, the “control information”of the present specification is not limited to “EHT-signal”, and“EHT-signal” may be proposed as an example of the “control information”.In addition, when indicated as “control information (i.e., EHT-signal)”,it may also mean that “EHT-signal” is proposed as an example of the“control information”.

Technical features described individually in one figure in the presentspecification may be individually implemented, or may be simultaneouslyimplemented.

The following example of the present specification may be applied tovarious wireless communication systems. For example, the followingexample of the present specification may be applied to a wireless localarea network (WLAN) system. For example, the present specification maybe applied to the IEEE 802.11a/g/n/ac standard or the IEEE 802.11axstandard. In addition, the present specification may also be applied tothe newly proposed EHT standard or IEEE 802.11be standard. In addition,the example of the present specification may also be applied to a newWLAN standard enhanced from the EHT standard or the IEEE 802.11bestandard. In addition, the example of the present specification may beapplied to a mobile communication system. For example, it may be appliedto a mobile communication system based on long term evolution (LTE)depending on a 3rd generation partnership project (3GPP) standard andbased on evolution of the LTE. In addition, the example of the presentspecification may be applied to a communication system of a 5G NRstandard based on the 3GPP standard.

Hereinafter, in order to describe a technical feature of the presentspecification, a technical feature applicable to the presentspecification will be described.

FIG. 1 shows an example of a transmitting apparatus and/or receivingapparatus of the present specification.

In the example of FIG. 1 , various technical features described belowmay be performed. FIG. 1 relates to at least one station (STA). Forexample, STAs 110 and 120 of the present specification may also becalled in various terms such as a mobile terminal, a wireless device, awireless transmit/receive unit (WTRU), a user equipment (UE), a mobilestation (MS), a mobile subscriber unit, or simply a user. The STAs 110and 120 of the present specification may also be called in various termssuch as a network, a base station, a node-B, an access point (AP), arepeater, a router, a relay, or the like. The STAs 110 and 120 of thepresent specification may also be referred to as various names such as areceiving apparatus, a transmitting apparatus, a receiving STA, atransmitting STA, a receiving device, a transmitting device, or thelike.

For example, the STAs 110 and 120 may serve as an AP or a non-AP. Thatis, the STAs 110 and 120 of the present specification may serve as theAP and/or the non-AP.

STAs 110 and 120 of the present specification may support variouscommunication standards together in addition to the IEEE 802.11standard. For example, a communication standard (e.g., LTE, LTE-A, 5G NRstandard) or the like based on the 3GPP standard may be supported. Inaddition, the STA of the present specification may be implemented asvarious devices, such as a mobile phone, a vehicle, a personal computer,or the like. In addition, the STA of the present specification maysupport communication for various communication services such as voicecalls, video calls, data communication, and self-driving(autonomous-driving), or the like.

The STAs 110 and 120 of the present specification may include a mediumaccess control (MAC) conforming to the IEEE 802.11 standard and aphysical layer interface for a radio medium.

The STAs 110 and 120 will be described below with reference to asub-figure (a) of FIG. 1 .

The first STA 110 may include a processor 111, a memory 112, and atransceiver 113. The illustrated process, memory, and transceiver may beimplemented individually as separate chips, or at least twoblocks/functions may be implemented through a single chip.

The transceiver 113 of the first STA performs a signaltransmission/reception operation. Specifically, an IEEE 802.11 packet(e.g., IEEE 802.11a/b/g/n/ac/ax/be, etc.) may be transmitted/received.

For example, the first STA 110 may perform an operation intended by anAP. For example, the processor 111 of the AP may receive a signalthrough the transceiver 113, process a reception (RX) signal, generate atransmission (TX) signal, and provide control for signal transmission.The memory 112 of the AP may store a signal (e.g., RX signal) receivedthrough the transceiver 113, and may store a signal (e.g., TX signal) tobe transmitted through the transceiver.

For example, the second STA 120 may perform an operation intended by anon-AP STA. For example, a transceiver 123 of a non-AP performs a signaltransmission/reception operation. Specifically, an IEEE 802.11 packet(e.g., IEEE 802.11a/b/g/n/ac/ax/be packet, etc.) may betransmitted/received.

For example, a processor 121 of the non-AP STA may receive a signalthrough the transceiver 123, process an RX signal, generate a TX signal,and provide control for signal transmission. A memory 122 of the non-APSTA may store a signal (e.g., RX signal) received through thetransceiver 123, and may store a signal (e.g., TX signal) to betransmitted through the transceiver.

For example, an operation of a device indicated as an AP in thespecification described below may be performed in the first STA 110 orthe second STA 120. For example, if the first STA 110 is the AP, theoperation of the device indicated as the AP may be controlled by theprocessor 111 of the first STA 110, and a related signal may betransmitted or received through the transceiver 113 controlled by theprocessor 111 of the first STA 110. In addition, control informationrelated to the operation of the AP or a TX/RX signal of the AP may bestored in the memory 112 of the first STA 110. In addition, if thesecond STA 120 is the AP, the operation of the device indicated as theAP may be controlled by the processor 121 of the second STA 120, and arelated signal may be transmitted or received through the transceiver123 controlled by the processor 121 of the second STA 120. In addition,control information related to the operation of the AP or a TX/RX signalof the AP may be stored in the memory 122 of the second STA 120.

For example, in the specification described below, an operation of adevice indicated as a non-AP (or user-STA) may be performed in the firstSTA 110 or the second STA 120. For example, if the second STA 120 is thenon-AP, the operation of the device indicated as the non-AP may becontrolled by the processor 121 of the second STA 120, and a relatedsignal may be transmitted or received through the transceiver 123controlled by the processor 121 of the second STA 120. In addition,control information related to the operation of the non-AP or a TX/RXsignal of the non-AP may be stored in the memory 122 of the second STA120. For example, if the first STA 110 is the non-AP, the operation ofthe device indicated as the non-AP may be controlled by the processor111 of the first STA 110, and a related signal may be transmitted orreceived through the transceiver 113 controlled by the processor 111 ofthe first STA 110. In addition, control information related to theoperation of the non-AP or a TX/RX signal of the non-AP may be stored inthe memory 112 of the first STA 110.

In the specification described below, a device called a(transmitting/receiving) STA, a first STA, a second STA, a STA1, a STA2,an AP, a first AP, a second AP, an AP1, an AP2, a(transmitting/receiving) terminal, a (transmitting/receiving) device, a(transmitting/receiving) apparatus, a network, or the like may imply theSTAs 110 and 120 of FIG. 1 . For example, a device indicated as, withouta specific reference numeral, the (transmitting/receiving) STA, thefirst STA, the second STA, the STA1, the STA2, the AP, the first AP, thesecond AP, the AN, the AP2, the (transmitting/receiving) terminal, the(transmitting/receiving) device, the (transmitting/receiving) apparatus,the network, or the like may imply the STAs 110 and 120 of FIG. 1 . Forexample, in the following example, an operation in which various STAstransmit/receive a signal (e.g., a PPDU) may be performed in thetransceivers 113 and 123 of FIG. 1 . In addition, in the followingexample, an operation in which various STAs generate a TX/RX signal orperform data processing and computation in advance for the TX/RX signalmay be performed in the processors 111 and 121 of FIG. 1 . For example,an example of an operation for generating the TX/RX signal or performingthe data processing and computation in advance may include: 1) anoperation ofdetermining/obtaining/configuring/computing/decoding/encoding bitinformation of a sub-field (SIG, STF, LTF, Data) included in a PPDU; 2)an operation of determining/configuring/obtaining a time resource orfrequency resource (e.g., a subcarrier resource) or the like used forthe sub-field (SIG, STF, LTF, Data) included the PPDU; 3) an operationof determining/configuring/obtaining a specific sequence (e.g., a pilotsequence, an STF/LTF sequence, an extra sequence applied to SIG) or thelike used for the sub-field (SIG, STF, LTF, Data) field included in thePPDU; 4) a power control operation and/or power saving operation appliedfor the STA; and 5) an operation related todetermining/obtaining/configuring/decoding/encoding or the like of anACK signal. In addition, in the following example, a variety ofinformation used by various STAs fordetermining/obtaining/configuring/computing/decoding/decoding a TX/RXsignal (e.g., information related to a field/subfield/controlfield/parameter/power or the like) may be stored in the memories 112 and122 of FIG. 1 .

The aforementioned device/STA of the sub-figure (a) of FIG. 1 may bemodified as shown in the sub-figure (b) of FIG. 1 . Hereinafter, theSTAs 110 and 120 of the present specification will be described based onthe sub-figure (b) of FIG. 1 .

For example, the transceivers 113 and 123 illustrated in the sub-figure(b) of FIG. 1 may perform the same function as the aforementionedtransceiver illustrated in the sub-figure (a) of FIG. 1 . For example,processing chips 114 and 124 illustrated in the sub-figure (b) of FIG. 1may include the processors 111 and 121 and the memories 112 and 122. Theprocessors 111 and 121 and memories 112 and 122 illustrated in thesub-figure (b) of FIG. 1 may perform the same function as theaforementioned processors 111 and 121 and memories 112 and 122illustrated in the sub-figure (a) of FIG. 1 .

A mobile terminal, a wireless device, a wireless transmit/receive unit(WTRU), a user equipment (UE), a mobile station (MS), a mobilesubscriber unit, a user, a user STA, a network, a base station, aNode-B, an access point (AP), a repeater, a router, a relay, a receivingunit, a transmitting unit, a receiving STA, a transmitting STA, areceiving device, a transmitting device, a receiving apparatus, and/or atransmitting apparatus, which are described below, may imply the STAs110 and 120 illustrated in the sub-figure (a)/(b) of FIG. 1 , or mayimply the processing chips 114 and 124 illustrated in the sub-figure (b)of FIG. 1 . That is, a technical feature of the present specificationmay be performed in the STAs 110 and 120 illustrated in the sub-figure(a)/(b) of FIG. 1 , or may be performed only in the processing chips 114and 124 illustrated in the sub-figure (b) of FIG. 1 . For example, atechnical feature in which the transmitting STA transmits a controlsignal may be understood as a technical feature in which a controlsignal generated in the processors 111 and 121 illustrated in thesub-figure (a)/(b) of FIG. 1 is transmitted through the transceivers 113and 123 illustrated in the sub-figure (a)/(b) of FIG. 1 . Alternatively,the technical feature in which the transmitting STA transmits thecontrol signal may be understood as a technical feature in which thecontrol signal to be transferred to the transceivers 113 and 123 isgenerated in the processing chips 114 and 124 illustrated in thesub-figure (b) of FIG. 1 .

For example, a technical feature in which the receiving STA receives thecontrol signal may be understood as a technical feature in which thecontrol signal is received by means of the transceivers 113 and 123illustrated in the sub-figure (a) of FIG. 1 . Alternatively, thetechnical feature in which the receiving STA receives the control signalmay be understood as the technical feature in which the control signalreceived in the transceivers 113 and 123 illustrated in the sub-figure(a) of FIG. 1 is obtained by the processors 111 and 121 illustrated inthe sub-figure (a) of FIG. 1 . Alternatively, the technical feature inwhich the receiving STA receives the control signal may be understood asthe technical feature in which the control signal received in thetransceivers 113 and 123 illustrated in the sub-figure (b) of FIG. 1 isobtained by the processing chips 114 and 124 illustrated in thesub-figure (b) of FIG. 1 .

Referring to the sub-figure (b) of FIG. 1 , software codes 115 and 125may be included in the memories 112 and 122. The software codes 115 and126 may include instructions for controlling an operation of theprocessors 111 and 121. The software codes 115 and 125 may be includedas various programming languages.

The processors 111 and 121 or processing chips 114 and 124 of FIG. 1 mayinclude an application-specific integrated circuit (ASIC), otherchipsets, a logic circuit and/or a data processing device. The processormay be an application processor (AP). For example, the processors 111and 121 or processing chips 114 and 124 of FIG. 1 may include at leastone of a digital signal processor (DSP), a central processing unit(CPU), a graphics processing unit (GPU), and a modulator and demodulator(modem). For example, the processors 111 and 121 or processing chips 114and 124 of FIG. 1 may be SNAPDRAGON™ series of processors made byQualcomm®, EXYNOS™ series of processors made by Samsung®, A series ofprocessors made by Apple®, HELIO™ series of processors made byMediaTek®, ATOM™ series of processors made by Intel® or processorsenhanced from these processors.

In the present specification, an uplink may imply a link forcommunication from a non-AP STA to an SP STA, and an uplinkPPDU/packet/signal or the like may be transmitted through the uplink. Inaddition, in the present specification, a downlink may imply a link forcommunication from the AP STA to the non-AP STA, and a downlinkPPDU/packet/signal or the like may be transmitted through the downlink.

FIG. 2 is a conceptual view illustrating the structure of a wirelesslocal area network (WLAN).

An upper part of FIG. 2 illustrates the structure of an infrastructurebasic service set (B SS) of institute of electrical and electronicengineers (i.e. EE) 802.11.

Referring the upper part of FIG. 2 , the wireless LAN system may includeone or more infrastructure BSSs 200 and 205 (hereinafter, referred to asBSS). The BSSs 200 and 205 as a set of an AP and a STA such as an accesspoint (AP) 225 and a station (STA1) 200-1 which are successfullysynchronized to communicate with each other are not concepts indicatinga specific region. The BSS 205 may include one or more STAs 205-1 and205-2 which may be joined to one AP 230.

The BSS may include at least one STA, APs providing a distributionservice, and a distribution system (DS) 210 connecting multiple APs.

The distribution system 210 may implement an extended service set (ESS)240 extended by connecting the multiple BSSs 200 and 205. The ESS 240may be used as a term indicating one network configured by connectingone or more APs 225 or 230 through the distribution system 210. The APincluded in one ESS 240 may have the same service set identification(SSID).

A portal 220 may serve as a bridge which connects the wireless LANnetwork (i.e.EE 802.11) and another network (e.g., 802.X).

In the BSS illustrated in the upper part of FIG. 2 , a network betweenthe APs 225 and 230 and a network between the APs 225 and 230 and theSTAs 200-1, 205-1, and 205-2 may be implemented. However, the network isconfigured even between the STAs without the APs 225 and 230 to performcommunication. A network in which the communication is performed byconfiguring the network even between the STAs without the APs 225 and230 is defined as an Ad-Hoc network or an independent basic service set(IBSS).

A lower part of FIG. 2 illustrates a conceptual view illustrating theIBSS.

Referring to the lower part of FIG. 2 , the IBSS is a BSS that operatesin an Ad-Hoc mode. Since the IBSS does not include the access point(AP), a centralized management entity that performs a managementfunction at the center does not exist. That is, in the IBSS, STAs 250-1,250-2, 250-3, 255-4, and 255-5 are managed by a distributed manner. Inthe IBSS, all STAs 250-1, 250-2, 250-3, 255-4, and 255-5 may beconstituted by movable STAs and are not permitted to access the DS toconstitute a self-contained network.

FIG. 3 illustrates a general link setup process.

In S310, a STA may perform a network discovery operation. The networkdiscovery operation may include a scanning operation of the STA. Thatis, to access a network, the STA needs to discover a participatingnetwork. The STA needs to identify a compatible network beforeparticipating in a wireless network, and a process of identifying anetwork present in a particular area is referred to as scanning Scanningmethods include active scanning and passive scanning.

FIG. 3 illustrates a network discovery operation including an activescanning process. In active scanning, a STA performing scanningtransmits a probe request frame and waits for a response to the proberequest frame in order to identify which AP is present around whilemoving to channels. A responder transmits a probe response frame as aresponse to the probe request frame to the STA having transmitted theprobe request frame. Here, the responder may be a STA that transmits thelast beacon frame in a BSS of a channel being scanned. In the BSS, sincean AP transmits a beacon frame, the AP is the responder. In an IBSS,since STAs in the IBSS transmit a beacon frame in turns, the responderis not fixed. For example, when the STA transmits a probe request framevia channel 1 and receives a probe response frame via channel 1, the STAmay store BSS-related information included in the received proberesponse frame, may move to the next channel (e.g., channel 2), and mayperform scanning (e.g., transmits a probe request and receives a proberesponse via channel 2) by the same method.

Although not shown in FIG. 3 , scanning may be performed by a passivescanning method. In passive scanning, a STA performing scanning may waitfor a beacon frame while moving to channels. A beacon frame is one ofmanagement frames in IEEE 802.11 and is periodically transmitted toindicate the presence of a wireless network and to enable the STAperforming scanning to find the wireless network and to participate inthe wireless network. In a BSS, an AP serves to periodically transmit abeacon frame. In an IBSS, STAs in the IBSS transmit a beacon frame inturns. Upon receiving the beacon frame, the STA performing scanningstores information related to a BSS included in the beacon frame andrecords beacon frame information in each channel while moving to anotherchannel. The STA having received the beacon frame may store BSS-relatedinformation included in the received beacon frame, may move to the nextchannel, and may perform scanning in the next channel by the samemethod.

After discovering the network, the STA may perform an authenticationprocess in S320. The authentication process may be referred to as afirst authentication process to be clearly distinguished from thefollowing security setup operation in S340. The authentication processin S320 may include a process in which the STA transmits anauthentication request frame to the AP and the AP transmits anauthentication response frame to the STA in response. The authenticationframes used for an authentication request/response are managementframes.

The authentication frames may include information related to anauthentication algorithm number, an authentication transaction sequencenumber, a status code, a challenge text, a robust security network(RSN), and a finite cyclic group.

The STA may transmit the authentication request frame to the AP. The APmay determine whether to allow the authentication of the STA based onthe information included in the received authentication request frame.The AP may provide the authentication processing result to the STA viathe authentication response frame.

When the STA is successfully authenticated, the STA may perform anassociation process in S330. The association process includes a processin which the STA transmits an association request frame to the AP andthe AP transmits an association response frame to the STA in response.The association request frame may include, for example, informationrelated to various capabilities, a beacon listen interval, a service setidentifier (SSID), a supported rate, a supported channel, RSN, amobility domain, a supported operating class, a traffic indication map(TIM) broadcast request, and an interworking service capability. Theassociation response frame may include, for example, information relatedto various capabilities, a status code, an association ID (AID), asupported rate, an enhanced distributed channel access (EDCA) parameterset, a received channel power indicator (RCPI), a receivedsignal-to-noise indicator (RSNI), a mobility domain, a timeout interval(association comeback time), an overlapping BSS scanning parameter, aTIM broadcast response, and a QoS map.

In S340, the STA may perform a security setup process. The securitysetup process in S340 may include a process of setting up a private keythrough four-way handshaking, for example, through an extensibleauthentication protocol over LAN (EAPOL) frame.

FIG. 4 illustrates an example of a PPDU used in an IEEE standard.

As illustrated, various types of PHY protocol data units (PPDUs) areused in IEEE a/g/n/ac standards. Specifically, an LTF and a STF includea training signal, a SIG-A and a SIG-B include control information for areceiving STA, and a data field includes user data corresponding to aPSDU (MAC PDU/aggregated MAC PDU).

FIG. 4 also includes an example of an HE PPDU according to IEEE802.11ax. The HE PPDU according to FIG. 4 is an illustrative PPDU formultiple users. An HE-SIG-B may be included only in a PPDU for multipleusers, and an HE-SIG-B may be omitted in a PPDU for a single user.

As illustrated in FIG. 4 , the HE-PPDU for multiple users (MUs) mayinclude a legacy-short training field (L-STF), a legacy-long trainingfield (L-LTF), a legacy-signal (L-SIG), a high efficiency-signal A(HE-SIG A), a high efficiency-signal-B (HE-SIG B), a highefficiency-short training field (HE-STF), a high efficiency-longtraining field (HE-LTF), a data field (alternatively, an MAC payload),and a packet extension (PE) field. The respective fields may betransmitted for illustrated time periods (i.e., 4 or 8 μs).

Hereinafter, a resource unit (RU) used for a PPDU is described. An RUmay include a plurality of subcarriers (or tones). An RU may be used totransmit a signal to a plurality of STAs according to OFDMA. Further, anRU may also be defined to transmit a signal to one STA. An RU may beused for an STF, an LTF, a data field, or the like.

FIG. 5 illustrates a layout of resource units (RUs) used in a band of 20MHz.

As illustrated in FIG. 5 , resource units (RUs) corresponding todifferent numbers of tones (i.e., subcarriers) may be used to form somefields of an HE-PPDU. For example, resources may be allocated inillustrated RUs for an HE-STF, an HE-LTF, and a data field.

As illustrated in the uppermost part of FIG. 5 , a 26-unit (i.e., a unitcorresponding to 26 tones) may be disposed. Six tones may be used for aguard band in the leftmost band of the 20 MHz band, and five tones maybe used for a guard band in the rightmost band of the 20 MHz band.Further, seven DC tones may be inserted in a center band, that is, a DCband, and a 26-unit corresponding to 13 tones on each of the left andright sides of the DC band may be disposed. A 26-unit, a 52-unit, and a106-unit may be allocated to other bands. Each unit may be allocated fora receiving STA, that is, a user.

The layout of the RUs in FIG. 5 may be used not only for a multipleusers (MUs) but also for a single user (SU), in which case one 242-unitmay be used and three DC tones may be inserted as illustrated in thelowermost part of FIG. 5 .

Although FIG. 5 proposes RUs having various sizes, that is, a 26-RU, a52-RU, a 106-RU, and a 242-RU, specific sizes of RUs may be extended orincreased. Therefore, the present embodiment is not limited to thespecific size of each RU (i.e., the number of corresponding tones).

FIG. 6 illustrates a layout of RUs used in a band of 40 MHz.

Similarly to FIG. 5 in which RUs having various sizes are used, a 26-RU,a 52-RU, a 106-RU, a 242-RU, a 484-RU, and the like may be used in anexample of FIG. 6 . Further, five DC tones may be inserted in a centerfrequency, 12 tones may be used for a guard band in the leftmost band ofthe 40 MHz band, and 11 tones may be used for a guard band in therightmost band of the 40 MHz band.

As illustrated in FIG. 6 , when the layout of the RUs is used for asingle user, a 484-RU may be used. The specific number of RUs may bechanged similarly to FIG. 5 .

FIG. 7 illustrates a layout of RUs used in a band of 80 MHz.

Similarly to FIG. 5 and FIG. 6 in which RUs having various sizes areused, a 26-RU, a 52-RU, a 106-RU, a 242-RU, a 484-RU, a 996-RU, and thelike may be used in an example of FIG. 7 . Further, seven DC tones maybe inserted in the center frequency, 12 tones may be used for a guardband in the leftmost band of the 80 MHz band, and 11 tones may be usedfor a guard band in the rightmost band of the 80 MHz band. In addition,a 26-RU corresponding to 13 tones on each of the left and right sides ofthe DC band may be used.

As illustrated in FIG. 7 , when the layout of the RUs is used for asingle user, a 996-RU may be used, in which case five DC tones may beinserted.

The RU described in the present specification may be used in uplink (UL)communication and downlink (DL) communication. For example, when UL-MUcommunication which is solicited by a trigger frame is performed, atransmitting STA (e.g., an AP) may allocate a first RU (e.g.,26/52/106/242-RU, etc.) to a first STA through the trigger frame, andmay allocate a second RU (e.g., 26/52/106/242-RU, etc.) to a second STA.Thereafter, the first STA may transmit a first trigger-based PPDU basedon the first RU, and the second STA may transmit a second trigger-basedPPDU based on the second RU. The first/second trigger-based PPDU istransmitted to the AP at the same (or overlapped) time period.

For example, when a DL MU PPDU is configured, the transmitting STA(e.g., AP) may allocate the first RU (e.g., 26/52/106/242-RU. etc.) tothe first STA, and may allocate the second RU (e.g., 26/52/106/242-RU,etc.) to the second STA. That is, the transmitting STA (e.g., AP) maytransmit HE-STF, HE-LTF, and Data fields for the first STA through thefirst RU in one MU PPDU, and may transmit HE-STF, HE-LTF, and Datafields for the second STA through the second RU.

Information related to a layout of the RU may be signaled throughHE-SIG-B.

FIG. 8 illustrates a structure of an HE-SIG-B field.

As illustrated, an HE-SIG-B field 810 includes a common field 820 and auser-specific field 830. The common field 820 may include informationcommonly applied to all users (i.e., user STAs) which receive SIG-B. Theuser-specific field 830 may be called a user-specific control field.When the SIG-B is transferred to a plurality of users, the user-specificfield 830 may be applied only any one of the plurality of users.

As illustrated in FIG. 8 , the common field 820 and the user-specificfield 830 may be separately encoded.

The common field 820 may include RU allocation information of N*8 bits.For example, the RU allocation information may include informationrelated to a location of an RU. For example, when a 20 MHz channel isused as shown in FIG. 5 , the RU allocation information may includeinformation related to a specific frequency band to which a specific RU(26-RU/52-RU/106-RU) is arranged.

An example of a case in which the RU allocation information consists of8 bits is as follows.

TABLE 1 8 bits indices (B7 B6 B5 B4 Number B3 B2 B1 B0) #1 #2 #3 #4 #5#6 #7 #8 #9 of entries 00000000 26 26 26 26 26 26 26 26 26 1 00000001 2626 26 26 26 26 26 52 1 00000010 26 26 26 26 26 52 26 26 1 00000011 26 2626 26 26 52 52 1 00000100 26 26 52 26 26 26 26 26 1 00000101 26 26 52 2626 26 52 1 00000110 26 26 52 26 52 26 26 1 00000111 26 26 52 26 52 52 100001000 52 26 26 26 26 26 26 26 1

As shown the example of FIG. 5 , up to nine 26-RUs may be allocated tothe 20 MHz channel. When the RU allocation information of the commonfield 820 is set to “00000000” as shown in Table 1, the nine 26-RUs maybe allocated to a corresponding channel (i.e., 20 MHz). In addition,when the RU allocation information of the common field 820 is set to“00000001” as shown in Table 1, seven 26-RUs and one 52-RU are arrangedin a corresponding channel That is, in the example of FIG. 5 , the 52-RUmay be allocated to the rightmost side, and the seven 26-RUs may beallocated to the left thereof.

The example of Table 1 shows only some of RU locations capable ofdisplaying the RU allocation information.

For example, the RU allocation information may include an example ofTable 2 below.

TABLE 2 8 bits indices (B7 B6 B5 B4 Number B3 B2 B1 B0) #1 #2 #3 #4 #5#6 #7 #8 #9 of entries 01000y₂y₁y₀ 106 26 26 26 26 26 8 01001y₂y₁y₀ 10626 26 26 52 8

“01000y2y1y0” relates to an example in which a 106-RU is allocated tothe leftmost side of the 20 MHz channel, and five 26-RUs are allocatedto the right side thereof. In this case, a plurality of STAs (e.g.,user-STAs) may be allocated to the 106-RU, based on a MU-MIMO scheme.Specifically, up to 8 STAs (e.g., user-STAs) may be allocated to the106-RU, and the number of STAs (e.g., user-STAs) allocated to the 106-RUis determined based on 3-bit information (y2y1y0). For example, when the3-bit information (y2y1y0) is set to N, the number of STAs (e.g.,user-STAs) allocated to the 106-RU based on the MU-MIMO scheme may beN+1.

In general, a plurality of STAs (e.g., user STAs) different from eachother may be allocated to a plurality of RUs. However, the plurality ofSTAs (e.g., user STAs) may be allocated to one or more RUs having atleast a specific size (e.g., 106 subcarriers), based on the MU-MIMOscheme.

As shown in FIG. 8 , the user-specific field 830 may include a pluralityof user fields. As described above, the number of STAs (e.g., user STAs)allocated to a specific channel may be determined based on the RUallocation information of the common field 820. For example, when the RUallocation information of the common field 820 is “00000000”, one userSTA may be allocated to each of nine 26-RUs (e.g., nine user STAs may beallocated). That is, up to 9 user STAs may be allocated to a specificchannel through an OFDMA scheme. In other words, up to 9 user STAs maybe allocated to a specific channel through a non-MU-MIMO scheme.

For example, when RU allocation is set to “01000y2y1y0”, a plurality ofSTAs may be allocated to the 106-RU arranged at the leftmost sidethrough the MU-MIMO scheme, and five user STAs may be allocated to five26-RUs arranged to the right side thereof through the non-MU MIMOscheme. This case is specified through an example of FIG. 9 .

FIG. 9 illustrates an example in which a plurality of user STAs areallocated to the same RU through a MU-MIMO scheme.

For example, when RU allocation is set to “01000010” as shown in FIG. 9, a 106-RU may be allocated to the leftmost side of a specific channel,and five 26-RUs may be allocated to the right side thereof. In addition,three user STAs may be allocated to the 106-RU through the MU-MIMOscheme. As a result, since eight user STAs are allocated, theuser-specific field 830 of HE-SIG-B may include eight user fields.

The eight user fields may be expressed in the order shown in FIG. 9 . Inaddition, as shown in FIG. 8 , two user fields may be implemented withone user block field.

The user fields shown in FIG. 8 and FIG. 9 may be configured based ontwo formats. That is, a user field related to a MU-MIMO scheme may beconfigured in a first format, and a user field related to a non-MIMOscheme may be configured in a second format. Referring to the example ofFIG. 9 , a user field 1 to a user field 3 may be based on the firstformat, and a user field 4 to a user field 8 may be based on the secondformat. The first format or the second format may include bitinformation of the same length (e.g., 21 bits).

Each user field may have the same size (e.g., 21 bits). For example, theuser field of the first format (the first of the MU-MIMO scheme) may beconfigured as follows.

For example, a first bit (i.e., B0-B10) in the user field (i.e., 21bits) may include identification information (e.g., STA-ID, partial AID,etc.) of a user STA to which a corresponding user field is allocated. Inaddition, a second bit (i.e., B11-B14) in the user field (i.e., 21 bits)may include information related to a spatial configuration.Specifically, an example of the second bit (i.e., B11-B14) may be asshown in Table 3 and Table 4 below.

TABLE 3 N_(STS) N_(STS) N_(STS) N_(STS) N_(STS) N_(STS) N_(STS) N_(STS)Total Number N_(user) B3 . . . B0 [1] [2] [3] [4] [5] [6] [7] [8]N_(STS) of entries 2 0000-0011 1-4 1 2-5 10 0100-0110 2-4 2 4-60111-1000 3-4 3 6-7 1001 4 4 8 3 0000-0011 1-4 1 1 3-6 13 0100-0110 2-42 1 5-7 0111-1000 3-4 3 1 7-8 1001-1011 2-4 2 2 6-8 1100 3 3 2 8 40000-0011 1-4 1 1 1 4-7 11 0100-0110 2-4 2 1 1 6-8 0111 3 3 1 1 81000-1001 2-3 2 2 1 7-8 1010 2 2 2 2 8

TABLE 4 N_(STS) N_(STS) N_(STS) N_(STS) N_(STS) N_(STS) N_(STS) N_(STS)Total Number N_(user) B3 . . . B0 [1] [2] [3] [4] [5] [6] [7] [8]N_(STS) of entries 5 0000-0011 1-4 1 1 1 1 5-8 7 0100-0101 2-3 2 1 1 17-8 0110 2 2 2 1 1 8 6 0000-0010 1-3 1 1 1 1 1 6-8 4 0011 2 2 1 1 1 1 87 0000-0001 1-2 1 1 1 1 1 1 7-8 2 8 0000 1 1 1 1 1 1 1 1 8 1

As shown in Table 3 and/or Table 4, the second bit (e.g., B11-B14) mayinclude information related to the number of spatial streams allocatedto the plurality of user STAs which are allocated based on the MU-MIMOscheme. For example, when three user STAs are allocated to the 106-RUbased on the MU-MIMO scheme as shown in FIG. 9 , N_user is set to “3”.Therefore, values of N_STS[1], N_STS[2], and N_STS[3] may be determinedas shown in Table 3. For example, when a value of the second bit(B11-B14) is “0011”, it may be set to N_STS[1]=4, N_STS[2]=1,N_STS[3]=1. That is, in the example of FIG. 9 , four spatial streams maybe allocated to the user field 1, one spatial stream may be allocated tothe user field 1, and one spatial stream may be allocated to the userfield 3.

As shown in the example of Table 3 and/or Table 4, information (i.e.,the second bit, B11-B14) related to the number of spatial streams forthe user STA may consist of 4 bits. In addition, the information (i.e.,the second bit, B11-B14) on the number of spatial streams for the userSTA may support up to eight spatial streams. In addition, theinformation (i.e., the second bit, B11-B14) on the number of spatialstreams for the user STA may support up to four spatial streams for oneuser STA.

In addition, a third bit (i.e., B15-18) in the user field (i.e., 21bits) may include modulation and coding scheme (MCS) information. TheMCS information may be applied to a data field in a PPDU includingcorresponding SIG-B.

An MCS, MCS information, an MCS index, an MCS field, or the like used inthe present specification may be indicated by an index value. Forexample, the MCS information may be indicated by an index 0 to an index11. The MCS information may include information related to aconstellation modulation type (e.g., BPSK, QPSK, 16-QAM, 64-QAM,256-QAM, 1024-QAM, etc.) and information related to a coding rate (e.g.,1/2, 2/3, 3/4, 5/6e, etc.). Information related to a channel coding type(e.g., LCC or LDPC) may be excluded in the MCS information.

In addition, a fourth bit (i.e., B19) in the user field (i.e., 21 bits)may be a reserved field.

In addition, a fifth bit (i.e., B20) in the user field (i.e., 21 bits)may include information related to a coding type (e.g., BCC or LDPC).That is, the fifth bit (i.e., B20) may include information related to atype (e.g., BCC or LDPC) of channel coding applied to the data field inthe PPDU including the corresponding SIG-B.

The aforementioned example relates to the user field of the first format(the format of the MU-MIMO scheme). An example of the user field of thesecond format (the format of the non-MU-MIMO scheme) is as follows.

A first bit (e.g., B0-B10) in the user field of the second format mayinclude identification information of a user STA. In addition, a secondbit (e.g., B11-B13) in the user field of the second format may includeinformation related to the number of spatial streams applied to acorresponding RU. In addition, a third bit (e.g., B14) in the user fieldof the second format may include information related to whether abeamforming steering matrix is applied. A fourth bit (e.g., B15-B18) inthe user field of the second format may include modulation and codingscheme (MCS) information. In addition, a fifth bit (e.g., B19) in theuser field of the second format may include information related towhether dual carrier modulation (DCM) is applied. In addition, a sixthbit (i.e., B20) in the user field of the second format may includeinformation related to a coding type (e.g., BCC or LDPC).

FIG. 10 illustrates an operation based on UL-MU. As illustrated, atransmitting STA (e.g., an AP) may perform channel access throughcontending (e.g., a backoff operation), and may transmit a trigger frame1030. That is, the transmitting STA may transmit a PPDU including thetrigger frame 1030. Upon receiving the PPDU including the trigger frame,a trigger-based (TB) PPDU is transmitted after a delay corresponding toSIFS.

TB PPDUs 1041 and 1042 may be transmitted at the same time period, andmay be transmitted from a plurality of STAs (e.g., user STAs) havingAIDs indicated in the trigger frame 1030. An ACK frame 1050 for the TBPPDU may be implemented in various forms.

A specific feature of the trigger frame is described with reference toFIG. 11 to FIG. 13 . Even if UL-MU communication is used, an orthogonalfrequency division multiple access (OFDMA) scheme or a MU MIMO schememay be used, and the OFDMA and MU-MIMO schemes may be simultaneouslyused.

FIG. 11 illustrates an example of a trigger frame. The trigger frame ofFIG. 11 allocates a resource for uplink multiple-user (MU) transmission,and may be transmitted, for example, from an AP. The trigger frame maybe configured of a MAC frame, and may be included in a PPDU.

Each field shown in FIG. 11 may be partially omitted, and another fieldmay be added. In addition, a length of each field may be changed to bedifferent from that shown in the figure.

A frame control field 1110 of FIG. 11 may include information related toa MAC protocol version and extra additional control information. Aduration field 1120 may include time information for NAV configurationor information related to an identifier (e.g., AID) of a STA.

In addition, an RA field 1130 may include address information of areceiving STA of a corresponding trigger frame, and may be optionallyomitted. A TA field 1140 may include address information of a STA (e.g.,an AP) which transmits the corresponding trigger frame. A commoninformation field 1150 includes common control information applied tothe receiving STA which receives the corresponding trigger frame. Forexample, a field indicating a length of an L-SIG field of an uplink PPDUtransmitted in response to the corresponding trigger frame orinformation for controlling content of a SIG-A field (i.e., HE-SIG-Afield) of the uplink PPDU transmitted in response to the correspondingtrigger frame may be included. In addition, as common controlinformation, information related to a length of a CP of the uplink PPDUtransmitted in response to the corresponding trigger frame orinformation related to a length of an LTF field may be included.

In addition, per user information fields 1160 #1 to 1160 #Ncorresponding to the number of receiving STAs which receive the triggerframe of FIG. 11 are preferably included. The per user information fieldmay also be called an “allocation field”.

In addition, the trigger frame of FIG. 11 may include a padding field1170 and a frame check sequence field 1180.

Each of the per user information fields 1160 #1 to 1160 #N shown in FIG.11 may include a plurality of subfields.

FIG. 12 illustrates an example of a common information field of atrigger frame. A subfield of FIG. 12 may be partially omitted, and anextra subfield may be added. In addition, a length of each subfieldillustrated may be changed.

A length field 1210 illustrated has the same value as a length field ofan L-SIG field of an uplink PPDU transmitted in response to acorresponding trigger frame, and a length field of the L-SIG field ofthe uplink PPDU indicates a length of the uplink PPDU. As a result, thelength field 1210 of the trigger frame may be used to indicate thelength of the corresponding uplink PPDU.

In addition, a cascade identifier field 1220 indicates whether a cascadeoperation is performed. The cascade operation implies that downlink MUtransmission and uplink MU transmission are performed together in thesame TXOP. That is, it implies that downlink MU transmission isperformed and thereafter uplink MU transmission is performed after apre-set time (e.g., SIFS). During the cascade operation, only onetransmitting device (e.g., AP) may perform downlink communication, and aplurality of transmitting devices (e.g., non-APs) may perform uplinkcommunication.

A CS request field 1230 indicates whether a wireless medium state or aNAV or the like is necessarily considered in a situation where areceiving device which has received a corresponding trigger frametransmits a corresponding uplink PPDU.

An HE-SIG-A information field 1240 may include information forcontrolling content of a SIG-A field (i.e., HE-SIG-A field) of theuplink PPDU in response to the corresponding trigger frame.

A CP and LTF type field 1250 may include information related to a CPlength and LTF length of the uplink PPDU transmitted in response to thecorresponding trigger frame. A trigger type field 1260 may indicate apurpose of using the corresponding trigger frame, for example, typicaltriggering, triggering for beamforming, a request for block ACK/NACK, orthe like.

It may be assumed that the trigger type field 1260 of the trigger framein the present specification indicates a trigger frame of a basic typefor typical triggering. For example, the trigger frame of the basic typemay be referred to as a basic trigger frame.

FIG. 13 illustrates an example of a subfield included in a per userinformation field. A user information field 1300 of FIG. 13 may beunderstood as any one of the per user information fields 1160 #1 to 1160#N mentioned above with reference to FIG. 11 . A subfield included inthe user information field 1300 of FIG. 13 may be partially omitted, andan extra subfield may be added. In addition, a length of each subfieldillustrated may be changed.

A user identifier field 1310 of FIG. 13 indicates an identifier of a STA(i.e., receiving STA) corresponding to per user information. An exampleof the identifier may be the entirety or part of an associationidentifier (AID) value of the receiving STA.

In addition, an RU allocation field 1320 may be included. That is, whenthe receiving STA identified through the user identifier field 1310transmits a TB PPDU in response to the trigger frame, the TB PPDU istransmitted through an RU indicated by the RU allocation field 1320. Inthis case, the RU indicated by the RU allocation field 1320 may be an RUshown in FIG. 5 , FIG. 6 , and FIG. 7 .

The subfield of FIG. 13 may include a coding type field 1330. The codingtype field 1330 may indicate a coding type of the TB PPDU. For example,when BCC coding is applied to the TB PPDU, the coding type field 1330may be set to ‘1’, and when LDPC coding is applied, the coding typefield 1330 may be set to ‘0’.

In addition, the subfield of FIG. 13 may include an MCS field 1340. TheMCS field 1340 may indicate an MCS scheme applied to the TB PPDU. Forexample, when BCC coding is applied to the TB PPDU, the coding typefield 1330 may be set to ‘1’, and when LDPC coding is applied, thecoding type field 1330 may be set to ‘0’.

Hereinafter, a UL OFDMA-based random access (UORA) scheme will bedescribed.

FIG. 14 describes a technical feature of the UORA scheme.

A transmitting STA (e.g., an AP) may allocate six RU resources through atrigger frame as shown in FIG. 14 . Specifically, the AP may allocate a1st RU resource (AID 0, RU 1), a 2nd RU resource (AID 0, RU 2), a 3rd RUresource (AID 0, RU 3), a 4th RU resource (AID 2045, RU 4), a 5th RUresource (AID 2045, RU 5), and a 6th RU resource (AID 3, RU 6).Information related to the AID 0, AID 3, or AID 2045 may be included,for example, in the user identifier field 1310 of FIG. 13 . Informationrelated to the RU 1 to RU 6 may be included, for example, in the RUallocation field 1320 of FIG. 13 . AID=0 may imply a UORA resource foran associated STA, and AID=2045 may imply a UORA resource for anun-associated STA. Accordingly, the 1st to 3rd RU resources of FIG. 14may be used as a UORA resource for the associated STA, the 4th and 5thRU resources of FIG. 14 may be used as a UORA resource for theun-associated STA, and the 6th RU resource of FIG. 14 may be used as atypical resource for UL MU.

In the example of FIG. 14 , an OFDMA random access backoff (OBO) of aSTA1 is decreased to 0, and the STA1 randomly selects the 2nd RUresource (AID 0, RU 2). In addition, since an OBO counter of a STA2/3 isgreater than 0, an uplink resource is not allocated to the STA2/3. Inaddition, regarding a STA4 in FIG. 14 , since an AID (e.g., AID=3) ofthe STA4 is included in a trigger frame, a resource of the RU 6 isallocated without backoff.

Specifically, since the STA1 of FIG. 14 is an associated STA, the totalnumber of eligible RA RUs for the STA1 is 3 (RU 1, RU 2, and RU 3), andthus the STA1 decreases an OBO counter by 3 so that the OBO counterbecomes 0. In addition, since the STA2 of FIG. 14 is an associated STA,the total number of eligible RA RUs for the STA2 is 3 (RU 1, RU 2, andRU 3), and thus the STA2 decreases the OBO counter by 3 but the OBOcounter is greater than 0. In addition, since the STA3 of FIG. 14 is anun-associated STA, the total number of eligible RA RUs for the STA3 is 2(RU 4, RU 5), and thus the STA3 decreases the OBO counter by 2 but theOBO counter is greater than 0.

FIG. 15 illustrates an example of a channel used/supported/definedwithin a 2.4 GHz band.

The 2.4 GHz band may be called in other terms such as a first band. Inaddition, the 2.4 GHz band may imply a frequency domain in whichchannels of which a center frequency is close to 2.4 GHz (e.g., channelsof which a center frequency is located within 2.4 to 2.5 GHz) areused/supported/defined.

A plurality of 20 MHz channels may be included in the 2.4 GHz band. 20MHz within the 2.4 GHz may have a plurality of channel indices (e.g., anindex 1 to an index 14). For example, a center frequency of a 20 MHzchannel to which a channel index 1 is allocated may be 2.412 GHz, acenter frequency of a 20 MHz channel to which a channel index 2 isallocated may be 2.417 GHz, and a center frequency of a 20 MHz channelto which a channel index N is allocated may be (2.407+0.005*N) GHz. Thechannel index may be called in various terms such as a channel number orthe like. Specific numerical values of the channel index and centerfrequency may be changed.

FIG. 15 exemplifies 4 channels within a 2.4 GHz band. Each of 1st to 4thfrequency domains 1510 to 1540 shown herein may include one channel. Forexample, the 1st frequency domain 1510 may include a channel 1 (a 20 MHzchannel having an index 1). In this case, a center frequency of thechannel 1 may be set to 2412 MHz. The 2nd frequency domain 1520 mayinclude a channel 6. In this case, a center frequency of the channel 6may be set to 2437 MHz. The 3rd frequency domain 1530 may include achannel 11. In this case, a center frequency of the channel 11 may beset to 2462 MHz. The 4th frequency domain 1540 may include a channel 14.In this case, a center frequency of the channel 14 may be set to 2484MHz.

FIG. 16 illustrates an example of a channel used/supported/definedwithin a 5 GHz band.

The 5 GHz band may be called in other terms such as a second band or thelike. The 5 GHz band may imply a frequency domain in which channels ofwhich a center frequency is greater than or equal to 5 GHz and less than6 GHz (or less than 5.9 GHz) are used/supported/defined. Alternatively,the 5 GHz band may include a plurality of channels between 4.5 GHz and5.5 GHz. A specific numerical value shown in FIG. 16 may be changed.

A plurality of channels within the 5 GHz band include an unlicensednational information infrastructure (UNII)-1, a UNII-2, a UNII-3, and anISM. The INII-1 may be called UNII Low. The UNII-2 may include afrequency domain called UNII Mid and UNII-2Extended. The UNII-3 may becalled UNII-Upper.

A plurality of channels may be configured within the 5 GHz band, and abandwidth of each channel may be variously set to, for example, 20 MHz,40 MHz, 80 MHz, 160 MHz, or the like. For example, 5170 MHz to 5330 MHzfrequency domains/ranges within the UNII-1 and UNII-2 may be dividedinto eight 20 MHz channels. The 5170 MHz to 5330 MHz frequencydomains/ranges may be divided into four channels through a 40 MHzfrequency domain. The 5170 MHz to 5330 MHz frequency domains/ranges maybe divided into two channels through an 80 MHz frequency domain.Alternatively, the 5170 MHz to 5330 MHz frequency domains/ranges may bedivided into one channel through a 160 MHz frequency domain.

FIG. 17 illustrates an example of a channel used/supported/definedwithin a 6 GHz band.

The 6 GHz band may be called in other terms such as a third band or thelike. The 6 GHz band may imply a frequency domain in which channels ofwhich a center frequency is greater than or equal to 5.9 GHz areused/supported/defined. A specific numerical value shown in FIG. 17 maybe changed.

For example, the 20 MHz channel of FIG. 17 may be defined starting from5.940 GHz. Specifically, among 20 MHz channels of FIG. 17 , the leftmostchannel may have an index 1 (or a channel index, a channel number,etc.), and 5.945 GHz may be assigned as a center frequency. That is, acenter frequency of a channel of an index N may be determined as(5.940+0.005*N) GHz.

Accordingly, an index (or channel number) of the 2 MHz channel of FIG.17 may be 1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61,65, 69, 73, 77, 81, 85, 89, 93, 97, 101, 105, 109, 113, 117, 121, 125,129, 133, 137, 141, 145, 149, 153, 157, 161, 165, 169, 173, 177, 181,185, 189, 193, 197, 201, 205, 209, 213, 217, 221, 225, 229, 233. Inaddition, according to the aforementioned (5.940+0.005*N) GHz rule, anindex of the 40 MHz channel of FIG. 17 may be 3, 11, 19, 27, 35, 43, 51,59, 67, 75, 83, 91, 99, 107, 115, 123, 131, 139, 147, 155, 163, 171,179, 187, 195, 203, 211, 219, 227.

Although 20, 40, 80, and 160 MHz channels are illustrated in the exampleof FIG. 17 , a 240 MHz channel or a 320 MHz channel may be additionallyadded.

Hereinafter, a PPDU transmitted/received in a STA of the presentspecification will be described.

FIG. 18 illustrates an example of a PPDU used in the presentspecification.

The PPDU of FIG. 18 may be called in various terms such as an EHT PPDU,a TX PPDU, an RX PPDU, a first type or N-th type PPDU, or the like. Forexample, in the present specification, the PPDU or the EHT PPDU may becalled in various terms such as a TX PPDU, a RX PPDU, a first type orN-th type PPDU, or the like. In addition, the EHT PPDU may be used in anEHT system and/or a new WLAN system enhanced from the EHT system.

The PPDU of FIG. 18 may represent some or all of the PPDU types used inthe EHT system. For example, the example of FIG. 18 may be used for botha single-user (SU) mode and a multi-user (MU) mode, or may be used onlyfor the SU mode, or may be used only for the MU mode. For example, atrigger-based PPDU (TB) on the EHT system may be separately defined orconfigured based on the example of FIG. 18 . The trigger frame describedthrough at least one of FIGS. 10 to 14 and the UL-MU operation (e.g.,the TB PPDU transmission operation) started by the trigger frame may bedirectly applied to the EHT system.

In FIG. 18 , an L-STF to an EHT-LTF may be called a preamble or aphysical preamble, and may begenerated/transmitted/received/obtained/decoded in a physical layer.

A subcarrier spacing of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, andEHT-SIG fields of FIG. 18 may be determined as 312.5 kHz, and asubcarrier spacing of the EHT-STF, EHT-LTF, and Data fields may bedetermined as 78.125 kHz. That is, a tone index (or subcarrier index) ofthe L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG fields may beexpressed in unit of 312.5 kHz, and a tone index (or subcarrier index)of the EHT-STF, EHT-LTF, and Data fields may be expressed in unit of78.125 kHz.

In the PPDU of FIG. 18 , the L-LTF and the L-STF may be the same asthose in the conventional fields.

The L-SIG field of FIG. 18 may include, for example, bit information of24 bits. For example, the 24-bit information may include a rate field of4 bits, a reserved bit of 1 bit, a length field of 12 bits, a parity bitof 1 bit, and a tail bit of 6 bits. For example, the length field of 12bits may include information related to a length or time duration of aPPDU. For example, the length field of 12 bits may be determined basedon a type of the PPDU. For example, when the PPDU is a non-HT, HT, VHTPPDU or an EHT PPDU, a value of the length field may be determined as amultiple of 3. For example, when the PPDU is an HE PPDU, the value ofthe length field may be determined as “a multiple of 3”+1 or “a multipleof 3”+2. In other words, for the non-HT, HT, VHT PPDI or the EHT PPDU,the value of the length field may be determined as a multiple of 3, andfor the HE PPDU, the value of the length field may be determined as “amultiple of 3”+1 or “a multiple of 3”+2.

For example, the transmitting STA may apply BCC encoding based on a 1/2coding rate to the 24-bit information of the L-SIG field. Thereafter,the transmitting STA may obtain a BCC coding bit of 48 bits. BPSKmodulation may be applied to the 48-bit coding bit, thereby generating48 BPSK symbols. The transmitting STA may map the 48 BPSK symbols topositions except for a pilot subcarrier{subcarrier index −21, −7, +7,+21} and a DC subcarrier{subcarrier index 0}. As a result, the 48 BPSKsymbols may be mapped to subcarrier indices −26 to −22, −20 to −8, −6 to−1, +1 to +6, +8 to +20, and +22 to +26. The transmitting STA mayadditionally map a signal of {−1, −1, −1, 1} to a subcarrier index{−28,−27, +27, +28}. The aforementioned signal may be used for channelestimation on a frequency domain corresponding to {−28, −27, +27, +28}.

The transmitting STA may generate an RL-SIG generated in the same manneras the L-SIG. BPSK modulation may be applied to the RL-SIG. Thereceiving STA may know that the RX PPDU is the HE PPDU or the EHT PPDU,based on the presence of the RL-SIG.

A universal SIG (U-SIG) may be inserted after the RL-SIG of FIG. 18 .The U-SIG may be called in various terms such as a first SIG field, afirst SIG, a first type SIG, a control signal, a control signal field, afirst (type) control signal, or the like.

The U-SIG may include information of N bits, and may include informationfor identifying a type of the EHT PPDU. For example, the U-SIG may beconfigured based on two symbols (e.g., two contiguous OFDM symbols).Each symbol (e.g., OFDM symbol) for the U-SIG may have a duration of 4μs. Each symbol of the U-SIG may be used to transmit the 26-bitinformation. For example, each symbol of the U-SIG may betransmitted/received based on 52 data tomes and 4 pilot tones.

Through the U-SIG (or U-SIG field), for example, A-bit information(e.g., 52 un-coded bits) may be transmitted. A first symbol of the U-SIGmay transmit first X-bit information (e.g., 26 un-coded bits) of theA-bit information, and a second symbol of the U-SIG may transmit theremaining Y-bit information (e.g. 26 un-coded bits) of the A-bitinformation. For example, the transmitting STA may obtain 26 un-codedbits included in each U-SIG symbol. The transmitting STA may performconvolutional encoding (i.e., BCC encoding) based on a rate of R=1/2 togenerate 52-coded bits, and may perform interleaving on the 52-codedbits. The transmitting STA may perform BPSK modulation on theinterleaved 52-coded bits to generate 52 BPSK symbols to be allocated toeach U-SIG symbol. One U-SIG symbol may be transmitted based on 65 tones(subcarriers) from a subcarrier index −28 to a subcarrier index +28,except for a DC index 0. The 52 BPSK symbols generated by thetransmitting STA may be transmitted based on the remaining tones(subcarriers) except for pilot tones, i.e., tones −21, −7, +7, +21.

For example, the A-bit information (e.g., 52 un-coded bits) generated bythe U-SIG may include a CRC field (e.g., a field having a length of 4bits) and a tail field (e.g., a field having a length of 6 bits). TheCRC field and the tail field may be transmitted through the secondsymbol of the U-SIG. The CRC field may be generated based on 26 bitsallocated to the first symbol of the U-SIG and the remaining 16 bitsexcept for the CRC/tail fields in the second symbol, and may begenerated based on the conventional CRC calculation algorithm. Inaddition, the tail field may be used to terminate trellis of aconvolutional decoder, and may be set to, for example, “000000”.

The A-bit information (e.g., 52 un-coded bits) transmitted by the U-SIG(or U-SIG field) may be divided into version-independent bits andversion-dependent bits. For example, the version-independent bits mayhave a fixed or variable size. For example, the version-independent bitsmay be allocated only to the first symbol of the U-SIG, or theversion-independent bits may be allocated to both of the first andsecond symbols of the U-SIG. For example, the version-independent bitsand the version-dependent bits may be called in various terms such as afirst control bit, a second control bit, or the like.

For example, the version-independent bits of the U-SIG may include a PHYversion identifier of 3 bits. For example, the PHY version identifier of3 bits may include information related to a PHY version of a TX/RX PPDU.For example, a first value of the PHY version identifier of 3 bits mayindicate that the TX/RX PPDU is an EHT PPDU. In other words, when thetransmitting STA transmits the EHT PPDU, the PHY version identifier of 3bits may be set to a first value. In other words, the receiving STA maydetermine that the RX PPDU is the EHT PPDU, based on the PHY versionidentifier having the first value.

For example, the version-independent bits of the U-SIG may include aUL/DL flag field of 1 bit. A first value of the UL/DL flag field of 1bit relates to UL communication, and a second value of the UL/DL flagfield relates to DL communication.

For example, the version-independent bits of the U-SIG may includeinformation related to a TXOP length and information related to a BSScolor ID.

For example, when the EHT PPDU is divided into various types (e.g.,various types such as an EHT PPDU related to an SU mode, an EHT PPDUrelated to a MU mode, an EHT PPDU related to a TB mode, an EHT PPDUrelated to extended range transmission, or the like), informationrelated to the type of the EHT PPDU may be included in theversion-dependent bits of the U-SIG.

For example, the U-SIG may include: 1) a bandwidth field includinginformation related to a bandwidth; 2) a field including informationrelated to an MCS scheme applied to EHT-SIG; 3) an indication fieldincluding information related to whether a dual subcarrier modulation(DCM) scheme is applied to EHT-SIG; 4) a field including informationrelated to the number of symbol used for EHT-SIG; 5) a field includinginformation related to whether the EHT-SIG is generated across a fullband; 6) a field including information related to a type of EHT-LTF/STF;and 7) information related to a field indicating an EHT-LTF length and aCP length.

Preamble puncturing may be applied to the PPDU of FIG. 18 . The preamblepuncturing implies that puncturing is applied to part (e.g., a secondary20 MHz band) of the full band. For example, when an 80 MHz PPDU istransmitted, a STA may apply puncturing to the secondary 20 MHz band outof the 80 MHz band, and may transmit a PPDU only through a primary 20MHz band and a secondary 40 MHz band.

For example, a pattern of the preamble puncturing may be configured inadvance. For example, when a first puncturing pattern is applied,puncturing may be applied only to the secondary 20 MHz band within the80 MHz band. For example, when a second puncturing pattern is applied,puncturing may be applied to only any one of two secondary 20 MHz bandsincluded in the secondary 40 MHz band within the 80 MHz band. Forexample, when a third puncturing pattern is applied, puncturing may beapplied to only the secondary 20 MHz band included in the primary 80 MHzband within the 160 MHz band (or 80+80 MHz band). For example, when afourth puncturing is applied, puncturing may be applied to at least one20 MHz channel not belonging to a primary 40 MHz band in the presence ofthe primary 40 MHz band included in the 80 MHaz band within the 160 MHzband (or 80+80 MHz band).

Information related to the preamble puncturing applied to the PPDU maybe included in U-SIG and/or EHT-SIG. For example, a first field of theU-SIG may include information related to a contiguous bandwidth, andsecond field of the U-SIG may include information related to thepreamble puncturing applied to the PPDU.

For example, the U-SIG and the EHT-SIG may include the informationrelated to the preamble puncturing, based on the following method. Whena bandwidth of the PPDU exceeds 80 MHz, the U-SIG may be configuredindividually in unit of 80 MHz. For example, when the bandwidth of thePPDU is 160 MHz, the PPDU may include a first U-SIG for a first 80 MHzband and a second U-SIG for a second 80 MHz band. In this case, a firstfield of the first U-SIG may include information related to a 160 MHzbandwidth, and a second field of the first U-SIG may include informationrelated to a preamble puncturing (i.e., information related to apreamble puncturing pattern) applied to the first 80 MHz band. Inaddition, a first field of the second U-SIG may include informationrelated to a 160 MHz bandwidth, and a second field of the second U-SIGmay include information related to a preamble puncturing (i.e.,information related to a preamble puncturing pattern) applied to thesecond 80 MHz band. Meanwhile, an EHT-SIG contiguous to the first U-SIGmay include information related to a preamble puncturing applied to thesecond 80 MHz band (i.e., information related to a preamble puncturingpattern), and an EHT-SIG contiguous to the second U-SIG may includeinformation related to a preamble puncturing (i.e., information relatedto a preamble puncturing pattern) applied to the first 80 MHz band.

Additionally or alternatively, the U-SIG and the EHT-SIG may include theinformation related to the preamble puncturing, based on the followingmethod. The U-SIG may include information related to a preamblepuncturing (i.e., information related to a preamble puncturing pattern)for all bands. That is, the EHT-SIG may not include the informationrelated to the preamble puncturing, and only the U-SIG may include theinformation related to the preamble puncturing (i.e., the informationrelated to the preamble puncturing pattern).

The U-SIG may be configured in unit of 20 MHz. For example, when an 80MHz PPDU is configured, the U-SIG may be duplicated. That is, fouridentical U-SIGs may be included in the 80 MHz PPDU. PPDUs exceeding an80 MHz bandwidth may include different U-SIGs.

The EHT-SIG of FIG. 18 may include the technical feature of the HE-SIG-Bshown in the examples of FIGS. 8 to 9 as it is. The EHT-SIG may bereferred to by various names such as a second SIG field, a second SIG, asecond type SIG, a control signal, a control signal field, and a second(type) control signal.

The EHT-SIG may include N-bit information (e.g., 1-bit information)related to whether the EHT-PPDU supports the SU mode or the MU mode.

The EHT-SIG may be configured based on various MCS schemes. As describedabove, information related to an MCS scheme applied to the EHT-SIG maybe included in U-SIG. The EHT-SIG may be configured based on a DCMscheme. For example, among N data tones (e.g., 52 data tones) allocatedfor the EHT-SIG, a first modulation scheme may be applied to half ofconsecutive tones, and a second modulation scheme may be applied to theremaining half of the consecutive tones. That is, a transmitting STA mayuse the first modulation scheme to modulate specific control informationthrough a first symbol and allocate it to half of the consecutive tones,and may use the second modulation scheme to modulate the same controlinformation by using a second symbol and allocate it to the remaininghalf of the consecutive tones. As described above, information (e.g., a1-bit field) related to whether the DCM scheme is applied to the EHT-SIGmay be included in the U-SIG. An HE-STF of FIG. 18 may be used forimproving automatic gain control estimation in a multiple input multipleoutput (MIMO) environment or an OFDMA environment. An HE-LTF of FIG. 18may be used for estimating a channel in the MIMO environment or theOFDMA environment.

The EHT-STF of FIG. 18 may be set in various types. For example, a firsttype of STF (e.g., 1×STF) may be generated based on a first type STFsequence in which a non-zero coefficient is arranged with an interval of16 subcarriers. An STF signal generated based on the first type STFsequence may have a period of 0.8 μs, and a periodicity signal of 0.8 μsmay be repeated 5 times to become a first type STF having a length of 4μs. For example, a second type of STF (e.g., 2×STF) may be generatedbased on a second type STF sequence in which a non-zero coefficient isarranged with an interval of 8 subcarriers. An STF signal generatedbased on the second type STF sequence may have a period of 1.6 μs, and aperiodicity signal of 1.6 μs may be repeated 5 times to become a secondtype STF having a length of 8 μs. Hereinafter, an example of a sequencefor configuring an EHT-STF (i.e., an EHT-STF sequence) is proposed. Thefollowing sequence may be modified in various ways.

The EHT-STF may be configured based on the following sequence M.M={−1,−1,−1,1,1,1,−1,1,1,1,−1,1,1,−1,1}  <Equation 1>

The EHT-STF for the 20 MHz PPDU may be configured based on the followingequation. The following example may be a first type (i.e., 1×STF)sequence. For example, the first type sequence may be included in not atrigger-based (TB) PPDU but an EHT-PPDU. In the following equation,(a:b:c) may imply a duration defined as b tone intervals (i.e., asubcarrier interval) from a tone index (i.e., subcarrier index) ‘a’ to atone index ‘c’. For example, the equation 2 below may represent asequence defined as 16 tone intervals from a tone index −112 to a toneindex 112. Since a subcarrier spacing of 78.125 kHz is applied to theEHT-STR, the 16 tone intervals may imply that an EHT-STF coefficient (orelement) is arranged with an interval of 78.125*16=1250 kHz. Inaddition, * implies multiplication, and sqrt( ) implies a square root.In addition, j implies an imaginary number.EHT-STF(−112:16:112)={M}*(1+j)/sqrt(2)EHT-STF(0)=0  <Equation 2>

The EHT-STF for the 40 MHz PPDU may be configured based on the followingequation. The following example may be the first type (i.e., 1×STF)sequence.EH-STF(−240:16:240)={M,0,−M}*(1+j)/sqrt(2)  <Equation 3>

The EHT-STF for the 80 MHz PPDU may be configured based on the followingequation. The following example may be the first type (i.e., 1×STF)sequence.EHT-STF(−496:16:496)={M,1,−M,0,−M,1,−M}*(1+j)/sqrt(2)  <Equation 4>

The EHT-STF for the 160 MHz PPDU may be configured based on thefollowing equation. The following example may be the first type (i.e.,1×STF) sequence.EHT-STF(−1008:16:1008)={M,1,−M,0,−M,1,−M,0,−M,−1,M,0,−M,1,−M}*(1+j)/sqrt(2)  <Equation5>

In the EHT-STF for the 80+80 MHz PPDU, a sequence for lower 80 MHz maybe identical to Equation 4. In the EHT-STF for the 80+80 MHz PPDU, asequence for upper 80 MHz may be configured based on the followingequation.EHT-STF(−496:16:496)={−M,−1,M,0,−M,1,−M}*(1+j)/sqrt(2)  <Equation 6>

Equation 7 to Equation 11 below relate to an example of a second type(i.e., 2×STF) sequence.EHT-STF(−120:8:120)={M,0,−M}*(1+j)/sqrt(2)  <Equation 7>

The EHT-STF for the 40 MHz PPDU may be configured based on the followingequation.EHT-STF(−248:8:248)={M,−1,−M,0,M,−1,M}*(1+j)/sqrt(2)EHT-STF(−248)=0EHT-STF(248)=0  <Equation 8>

The EHT-STF for the 80 MHz PPDU may be configured based on the followingequation.EHT-STF(−504:8:504)={M,−1,M,−1,−M,−1,M,0,−M,1,M,1,−M,1,−M}*(1+j)/sqrt(2)  <Equation9>

The EHT-STF for the 160 MHz PPDU may be configured based on thefollowing equation.EHT-STF(−1016:16:1016)={M,−1,M,−1,−M,−1,M,0,−M,1,M,1,−M,1,−M,0,−M,1,−M,1,M,1,−M,0,−M,1,M,1,−M,1,−M}*(1+j)/sqrt(2)EHT-STF(−8)=0,EHT-STF(8)=0,EHT-STF(−1016)=0,EHT-STF(1016)=0  <Equation 10>

In the EHT-STF for the 80+80 MHz PPDU, a sequence for lower 80 MHz maybe identical to Equation 9. In the EHT-STF for the 80+80 MHz PPDU, asequence for upper 80 MHz may be configured based on the followingequation.EHT-STF(−504:8:504)={−M,1,−M,1,M,1,−M,0,−M,1,M,1,−M,1,−M}*(1+j)/sqrt(2)EHT-STF(−504)=0,EHT-STF(504)=0  <Equation 11>

The EHT-LTF may have first, second, and third types (i.e., 1×, 2×,4×LTF). For example, the first/second/third type LTF may be generatedbased on an LTF sequence in which a non-zero coefficient is arrangedwith an interval of 4/2/1 subcarriers. The first/second/third type LTFmay have a time length of 3.2/6.4/12.8 μs. In addition, a GI (e.g.,0.8/1/6/3.2 μs) having various lengths may be applied to thefirst/second/third type LTF.

Information related to a type of STF and/or LTF (information related toa GI applied to LTF is also included) may be included in a SIG-A fieldand/or SIG-B field or the like of FIG. 18 .

A PPDU (e.g., EHT-PPDU) of FIG. 18 may be configured based on theexample of FIG. 5 and FIG. 6 .

For example, an EHT PPDU transmitted on a 20 MHz band, i.e., a 20 MHzEHT PPDU, may be configured based on the RU of FIG. 5 . That is, alocation of an RU of EHT-STF, EHT-LTF, and data fields included in theEHT PPDU may be determined as shown in FIG. 5 .

An EHT PPDU transmitted on a 40 MHz band, i.e., a 40 MHz EHT PPDU, maybe configured based on the RU of FIG. 6 . That is, a location of an RUof EHT-STF, EHT-LTF, and data fields included in the EHT PPDU may bedetermined as shown in FIG. 6 .

Since the RU location of FIG. 6 corresponds to 40 MHz, a tone-plan for80 MHz may be determined when the pattern of FIG. 6 is repeated twice.That is, an 80 MHz EHT PPDU may be transmitted based on a new tone-planin which not the RU of FIG. 7 but the RU of FIG. 6 is repeated twice.

When the pattern of FIG. 6 is repeated twice, 23 tones (i.e., 11 guardtones+12 guard tones) may be configured in a DC region. That is, atone-plan for an 80 MHz EHT PPDU allocated based on OFDMA may have 23 DCtones. Unlike this, an 80 MHz EHT PPDU allocated based on non-OFDMA(i.e., a non-OFDMA full bandwidth 80 MHz PPDU) may be configured basedon a 996-RU, and may include 5 DC tones, 12 left guard tones, and 11right guard tones.

A tone-plan for 160/240/320 MHz may be configured in such a manner thatthe pattern of FIG. 6 is repeated several times.

The PPDU of FIG. 18 may be determined (or identified) as an EHT PPDUbased on the following method.

A receiving STA may determine a type of an RX PPDU as the EHT PPDU,based on the following aspect. For example, the RX PPDU may bedetermined as the EHT PPDU: 1) when a first symbol after an L-LTF signalof the RX PPDU is a BPSK symbol; 2) when RL-SIG in which the L-SIG ofthe RX PPDU is repeated is detected; and 3) when a result of applying“modulo 3” to a value of a length field of the L-SIG of the RX PPDU isdetected as “0”. When the RX PPDU is determined as the EHT PPDU, thereceiving STA may detect a type of the EHT PPDU (e.g., anSU/MU/Trigger-based/Extended Range type), based on bit informationincluded in a symbol after the RL-SIG of FIG. 18 . In other words, thereceiving STA may determine the RX PPDU as the EHT PPDU, based on: 1) afirst symbol after an L-LTF signal, which is a BPSK symbol; 2) RL-SIGcontiguous to the L-SIG field and identical to L-SIG; 3) L-SIG includinga length field in which a result of applying “modulo 3” is set to “0”;and 4) a 3-bit PHY version identifier of the aforementioned U-SIG (e.g.,a PHY version identifier having a first value).

For example, the receiving STA may determine the type of the RX PPDU asthe EHT PPDU, based on the following aspect. For example, the RX PPDUmay be determined as the HE PPDU: 1) when a first symbol after an L-LTFsignal is a BPSK symbol; 2) when RL-SIG in which the L-SIG is repeatedis detected; and 3) when a result of applying “modulo 3” to a value of alength field of the L-SIG is detected as “1” or “2”.

For example, the receiving STA may determine the type of the RX PPDU asa non-HT, HT, and VHT PPDU, based on the following aspect. For example,the RX PPDU may be determined as the non-HT, HT, and VHT PPDU: 1) when afirst symbol after an L-LTF signal is a BPSK symbol; and 2) when RL-SIGin which L-SIG is repeated is not detected. In addition, even if thereceiving STA detects that the RL-SIG is repeated, when a result ofapplying “modulo 3” to the length value of the L-SIG is detected as “0”,the RX PPDU may be determined as the non-HT, HT, and VHT PPDU.

In the following example, a signal represented as a (TX/RX/UL/DL)signal, a (TX/RX/UL/DL) frame, a (TX/RX/UL/DL) packet, a (TX/RX/UL/DL)data unit, (TX/RX/UL/DL) data, or the like may be a signaltransmitted/received based on the PPDU of FIG. 18 . The PPDU of FIG. 18may be used to transmit/receive frames of various types. For example,the PPDU of FIG. 18 may be used for a control frame. An example of thecontrol frame may include a request to send (RTS), a clear to send(CTS), a power save-poll (PS-poll), BlockACKReq, BlockAck, a null datapacket (NDP) announcement, and a trigger frame. For example, the PPDU ofFIG. 18 may be used for a management frame. An example of the managementframe may include a beacon frame, a (re-)association request frame, a(re-)association response frame, a probe request frame, and a proberesponse frame. For example, the PPDU of FIG. 18 may be used for a dataframe. For example, the PPDU of FIG. 18 may be used to simultaneouslytransmit at least two or more of the control frames, the managementframe, and the data frame.

FIG. 19 illustrates an example of a modified transmitting apparatusand/or receiving apparatus of the present specification.

Each device/STA of the sub-figure (a)/(b) of FIG. 1 may be modified asshown in FIG. 19. A transceiver 630 of FIG. 19 may be identical to thetransceivers 113 and 123 of FIG. 1 . The transceiver 630 of FIG. 19 mayinclude a receiver and a transmitter.

A processor 610 of FIG. 19 may be identical to the processors 111 and121 of FIG. 1 . Alternatively, the processor 610 of FIG. 19 may beidentical to the processing chips 114 and 124 of FIG. 1 .

A memory 620 of FIG. 19 may be identical to the memories 112 and 122 ofFIG. 1 . Alternatively, the memory 620 of FIG. 19 may be a separateexternal memory different from the memories 112 and 122 of FIG. 1 .

Referring to FIG. 19 , a power management module 611 manages power forthe processor 610 and/or the transceiver 630. A battery 612 suppliespower to the power management module 611. A display 613 outputs a resultprocessed by the processor 610. A keypad 614 receives inputs to be usedby the processor 610. The keypad 614 may be displayed on the display613. A SIM card 615 may be an integrated circuit which is used tosecurely store an international mobile subscriber identity (IMSI) andits related key, which are used to identify and authenticate subscriberson mobile telephony devices such as mobile phones and computers.

Referring to FIG. 19 , a speaker 640 may output a result related to asound processed by the processor 610. A microphone 641 may receive aninput related to a sound to be used by the processor 610.

In the following specification, an EHT standard or a PPDU according tothe EHT standard may be described.

To provide a higher data rate than 802.11ax, the EHT standard may beproposed. The EHT standard may support a wide bandwidth (e.g., abandwidth of 320 MHz or more), 16 streams, and/or a multi-link (ormulti-band) operation. Therefore, to support a transmission method basedon the EHT standard, a new frame format may be used. When a signal istransmitted using the new frame format through a 2.4/5/6 GHz band, notonly a receiver supporting the EHT standard but also conventional Wi-Fireceivers (or STAs) (e.g., receivers according to 802.11n/ac/ax) mayreceive the EHT signal (e.g., a wake-up radio (WUR) signal) transmittedthrough the 2.4/5/6 GHz band. For example, when a conventional Wi-Fireceiver (or STA) falsely detects a received EHT signal (e.g., WURsignal), the conventional Wi-Fi receiver may recognize/identify thereceived EHT signal as a signal (or packet) transmitted to theconventional Wi-Fi receiver. Accordingly, the conventional Wi-Fireceiver decodes the received EHT signal, and thus power may be wasted.

Hereinafter, when the EHT standard supports backward compatibility withconventional Wi-Fi, an embodiment of configuring an 11be preamble (apreamble based on an 802.11be standard (EHT)) may be proposed to preventa detection error.

A preamble of a PPDU based on the EHT standard may be variouslyconfigured. Hereinafter, an embodiment of configuring a preamble of aPPDU based on the EHT standard may be described. In addition, anembodiment of performing packet indication through a preamble of a PPDUbased on the EHT standard may also be described. Hereinafter, a PPDUbased on the EHT standard may be described as an EHT PPDU. However, theEHT PPDU is not limited to the EHT standard. The EHT PPDU may includenot only a PPDU based on 802.11be (i.e., the EHT standard) but also aPPDU based on a new standard advancing/evolving/extending from 802.11be.

FIG. 20 illustrates a format of an EHT PPDU.

Referring to FIG. 20 , an EHT PPDU 2000 may be configured using a frameformat of a PPDU based on 802.11ax. The EHT PPDU 2000 may include anL-part 2010 and an EHT part 2020.

The EHT PPDU 2000 may be configured in a structure in which the L-Part2010 is transmitted first before the EHT part 2020 for coexistence witha legacy STA (STA according to 802.11n/ac/ax).

According to an embodiment, the EHT part 2020 may include an RL-SIG, anEHT control field (e.g., a U-SIG (not shown), an EHT-SIG, an EHT-STF,and/or an EHT-LTF), and an EHT data field.

According to an embodiment, the EHT part 2020 may include an RL-SIG, anearly indication symbol (detection symbol), an EHT control field (e.g.,a U-SIG (not shown), an EHT-SIG, an EHT-STF, and an EHT-LTF), and an EHTdata field.

Although FIG. 20 shows an example in which an RL-SIG is used for asymbol following an L-SIG, the RL-SIG may be referred to by variousterms.

Hereinafter, a specific example of a preamble of an EHT PPDU may bedescribed. To support coexistence and backward compatibility with alegacy system (a system according to 802.11n/ac/ax) already operating,an EHT PPDU may be newly configured and be transmitted. In this case, itis possible to reduce false packet detection by a third-party device(e.g., an STA according to 802.11n/ac/ax) through a preamble of the EHTPPDU. In addition, it is possible to perform packet indication for theEHT PPDU through the preamble of the EHT PPDU. For example, a STAsupporting the EHT standard (hereinafter, EHT STA) may identify that areceived PPDU is a PPDU based on the EHT standard, based on a preambleof the received EHT PPDU. Hereinafter, a specific example of thepreamble of the EHT PPDU may be described with reference to first tofifth embodiments.

First Embodiment

According to a first embodiment, in the EHT standard, a frame formataccording to 802.11ax may be recycled. However, in the EHT standard,11be packet indication may be performed through the value of a lengthfield. That is, a STA (or a receiving STA) according to the EHT standardmay identify that the format of a received PPDU is an EHT PPDU based onthe value of the length field.

FIG. 21 illustrates another format of an EHT PPDU.

Referring to FIG. 21 , an EHT PPDU 2100 may include an L-STF 2110, anL-LTF 2120, an L-SIG 2130, an RL-SIG 2140, an EHT-SIG 2150, an EHT-SIG2160, an EHT-STF 2170, an EHT-LTF 2180, and/or an EHT-data 2190. The EHTPPDU 2100 may be related to the PPDU illustrated in FIG. 18 . Forexample, the EHT-SIG 2150 may be related to the U-SIG illustrated inFIG. 18 .

According to an embodiment, the EHT PPDU 2100 may include the RL-SIG2140 in which the L-SIG 2130 is repeated after the L-SIG 2130 as in802.11ax. In addition, a length field of the L-SIG 2130 and the RL-SIG2140 in the frame format of the EHT PPDU 2100 may be configured asfollows for packet classification.

1. According to an embodiment, the length field may be set to a valuesatisfying that the remainder is zero when the value of the length fieldis divided by 3. That is, the value of the length field may be set to avalue that produces 0 in a modulo (or modular) operation with 3. Thevalue of the length field may be set using an equation according to802.11ax. The value of the length field may be set by Equation 13.

$\begin{matrix}{{{Length} = {{\left\lceil \frac{{TXTIME} - {signalextension} - 20}{4} \right\rceil \times 3} - 3 - m}},} & \left\langle {{Equation}13} \right\rangle\end{matrix}$ m = 0

Referring to Equation 13, the value of the length field may be set basedon the transmission length (TXTIME) of the EHT PPDU 2100. Further, thevalue of signalextension may be set when signal extension is applied.For example, the value of signalextension may be set to 0 μs in 5 GHz or6 GHz when signal extension is applied. In addition, the value ofsignalextension may be set to 6 μs in 2.4 GHz when signal extension isapplied. A ┌x┐ operation may refer to ceil(x). The ┌x┐ operation mayrefer to a minimum integer equal to or greater than x.

2. According to an embodiment, BPSK modulation may be applied to theL-SIG 2130, the RL-SIG 2140, and/or the EHT-SIGs 2150 and 2160. Inaddition, the L-SIG 2130, the RL-SIG 2140, and/or the EHT-SIG 2150 and2160 may be configured by applying BCC 1/2. According to an embodiment,dual carrier modulation (DCM) may be applied to the EHT PPDU 2100.

As described above, the EHT PPDU may be transmitted by setting the valueof the length field included in the L-SIG and the RL-SIG to be differentfrom that in 802.11ax. In this case, it is possible to reduce errors ofSTAs according to 802.11n/ac/ax, which operate in a 5 GHz UNII band,recognizing the EHT PPDU as a frame transmitted to the STAs.

1. An 802.11n STA (hereinafter, 11n STA) may measure constellations oftwo symbols following the L-SIG for packet classification. In this case,when both of the constellations of the two symbols are QBPSK, the 11nSTA may determine the received packet (or PPDU) as a packet thereof(i.e., a PPDU of the 11n standard (hereinafter, 11n PPDU)). Therefore,when an RL-SIG symbol and an EHT-SIG symbol, which are symbols after theL-SIG, in the EHT PPDU are configured with BPSK symbols, the 11n STAdoes not recognize the constellations of the two symbols as QBPSK whenexamining the constellations, thus not recognizing the EHT PPDU (or EHTframe) as an 11n PPDU (or 11n frame). Accordingly, when the RL-SIGsymbol and the EHT-SIG symbol, which are symbols after the L-SIG, areconfigured with BPSK symbols, it is possible to prevent the 11n STA frommistaking the EHT PPDU as the 11n PPDU.

2. An 802.11ac STA (hereinafter, 11ac STA) may measure constellations oftwo symbols following the L-SIG for packet classification. In this case,when the constellations of the two symbols are BPSK and QBPSK, the 11acSTA may determine the received packet (or PPDU) as a packet thereof(i.e., a PPDU of the 11ac standard (hereinafter, 11n PPDU)). Therefore,as described above when the RL-SIG symbol and the EHT-SIG symbol, whichare symbols after the L-SIG, in the EHT PPDU are configured with BPSKsymbols, it is possible to prevent the 11ac STA from mistaking the EHTPPDU as an 11ac PPDU. That is, when receiving the EHT PPDU, the 11ac STAmay identify constellation mapping of the two symbols following theL-SIG. The 11ac STA may identify that the two symbols following theL-SIG are configured with BPSK. Accordingly, the 11ac STA may identifythat the constellation mapping of the two symbols (the RL-SIG symbol andthe EHT-SIG symbol) does not match constellation mapping of an 11acPPDU. Accordingly, the 11ac STA may identify that the received PPDU isnot an 11ac PPDU.

3. An 802.11ax STA (hereinafter, 11ax STA) may perform a two-stepverification process (repetition check and L-SIG content check) forpacket classification. First, the 11ax STA may identify/check whetherthe L-SIG is repeated. Subsequently, when the RL-SIG symbol istransmitted after the L-SIG, the 11ax STA may complete the repetitioncheck.

Next, the 11ax STA may perform the L-SIG content check. For example, theflax STA may identify that the result of applying “modulo 3” to thelength field of the L-SIG and the RL-SIG is set to “0”. In an flax PPDU(hereinafter, 11ax PPDU), the result of applying “modulo 3” to thelength field of the L-SIG and the RL-SIG may be set to “1” or “2”.Accordingly, the 11ax STA may identify that the result of performing theL-SIG content check on the received PPDU does not pass. When receivingthe EHT PPDU, the 11ax STA may not determine the EHT PPDU as an flaxPPDU (or 11ax frame). That is, it is possible to reduce false detectionby performing the two-step verification.

As described above, the frame format according to 802.11ax is used as itis for the EHT PPDU, thus simplifying implementation. That is, using theframe format according to 802.11ax is used facilitates implementation.However, since the EHT packet is determined through the content checkafter passing the repetition check, detection may take a longer timethan conventional detection.

4. When receiving the EHT PPDU (or EHT frame), an EHT STA mayidentify/check whether the L-SIG and the RL-SIG are repeated in the samemanner as the 11ax STA. Subsequently, the EHT STA may determine whetherthe value of the length field of the L-SIG is divisible by 3, therebydetermining whether the received PPDU is an EHT PPDU (or EHT frame). Inaddition, the EHT STA may combine the RL-SIG and the L-SIG and may thendetermine/decide that the received PPDU is an EHT PPDU (or EHT frame).The EHT STA may improve reception performance of the L-SIG by combiningthe RL-SIG and the L-SIG. According to an embodiment, the combiningprocess may be performed in terms of time or frequency. For example, thecombining process may be performed after fast Fourier transform (FFT) toimprove performance.

Second Embodiment

According to a second embodiment, an RL-SIG of an EHT PPDU may beconfigured by modifying an L-SIG bit or by applying polarization to anRL-SIG.

Similar to the EHT PPDU 2100 illustrated in FIG. 21 , in the EHT PPDU, afield following an L-SIG may be configured as the RL-SIG. In addition,the value of a length field of the L-SIG may be set to a value divisibleby 3. In this case, an example of the RL-SIG may be described below.

1. A data bit applied to the RL-SIG may be variously configured. Forexample, the data bit applied to the RL-SIG may be configured using anL-SIG data bit. The data bit applied to the RL-SIG may be configuredaccording to the following embodiments of A to C.

1-A. The data bit applied to the RL-SIG may be configured with acomplementary bit of the L-SIG data bit.

1-A-i) For example, 24 data bits of the L-SIG may be configured as {1 10 1 1 1 0 1 0 . . . 1 1 0}. Data bits of the RL-SIG may be configured as{0 0 1 0 0 0 1 0 1 . . . 0 0 1}. In this case, the largest Euclideandistance may be set between these two pieces of data.

1-A-ii) For example, when complementary bits are configured, acomplementary operation (or complementary process) may be applied onlyto remaining bits except for the length field of the L-SIG. Therefore,as described above, even if the complementary operation is applied, thevalue of the length field may be set to be divisible by 3.

1-A-iii) For example, a complementary bit for the length field may alsobe set to a number divisible by 3. In this case, the RL-SIG may beconfigured by applying a complementary operation to all bits of theL-SIG.

1-B. The RL-SIG may be configured using a data bit generated through anXOR operation of the data bit of the L-SIG and a designated (orspecific) bit or sequence.

1-B-i) For example, the specific bit may be configured with one bit(e.g., 1 or 0). Accordingly, the RL-SIG may be configured using a databit generated through an XOR operation of the one bit and the L-SIG databit.

1-B-ii) In another example, the RL-SIG may be configured using a databit generated/formed through an XOR operation with a 24-bit sequence, a12-bit sequence, or a sequence including bits of a length correspondingto remaining bits except for the length field.

For example, when the XOR operation is performed based on the 12-bitsequence, the 12-bit sequence may be configured as [1 0 0 0 0 1 0 1 0 11 1].

In another example, the sequence of bits except for the length field andthe 24-bit sequence may be generated by repeating the 12-bit sequence.In another example, the sequence of bits except for the length field andthe-24 bit sequence may be configured with a sequence that minimizes aPAPR.

1-C. Unlike the foregoing embodiment, to configure the RL-SIG, BPSKmodulation may be performed on the same data as the L-SIG. Subsequently,each modulated signal may be multiplied by a specific polarization(e.g., −1), thereby configuring RL-SIG.

2. Configuring the RL-SIG through the foregoing embodiment makes itpossible to reduce false alarms by legacy STAs (11n/11ac/11ax STAs) whenthe EHT PPDU (or EHT frame) is transmitted.

2-A. In 802.11n and 802.11ac, all constellations of two symbolsfollowing the L-SIG are set to BPSK. Therefore, according to theforegoing embodiment, when an 11n STA and an 11ac STA receive the EHTframe, it is possible to prevent the EHT frame from being falselydetected as an 11n PPDU or an 11ac PPDU. That is, the foregoingembodiment may prevent the 11n STA from erroneously determining the EHTPPDU as the 11n PPDU. In addition, the foregoing embodiment may preventthe 11ac STA from erroneously determining the EHT PPDU as the 11ac PPDU.

2-B. When receiving the EHT PPDU, an 11ax STA may identify, through arepetition check, that the RL-SIG is not configured with the same bit asthe L-SIG or is configured by applying a different polarization. Thatis, in the 11ax STA, the EHT PPDU may not pass the repetition check.Accordingly, it is possible to reduce an error of the 11ax STAdetermining the EHT PPDU as an 11ax PPDU. In addition, since the valueof the length field of the L-SIG is set to a value divisible by 3, eventhough the EHT PPDU passes the repetition check, the 11ax STA maydetermine that the EHT PPDU is not an 11ax PPDU in a content check.Accordingly, it is possible to reduce false detection errors of the 11axSTA.

Third Embodiment

According to a third embodiment, an EHT PPDU (or EHT frame) may beconfigured to include a symbol including information related to a frameformat after an RL-SIG.

FIG. 22 illustrates another format of an EHT PPDU.

Referring to FIG. 22 , an EHT PPDU 2200 may include an L-STF 2210, anL-LTF 2220, an L-SIG 2230, an RL-SIG 2240, an Ind_symbol 2250, anEHT-STF 2260, an EHT-LTF 2270, and/or an EHT-data 2280. The EHT PPDU2200 may be related to the PPDU illustrated in FIG. 18 . The Ind_symbol2250 may be related to the U-SIG illustrated in FIG. 18 .

According to an embodiment, the value of a length field of the L-SIG2230 may be set to a value divisible by 3. That is, the value of thelength field may be set to a value that produces 0 in a modulo (ormodular) operation with 3.

For the third embodiment, a frame structure of the EHT PPDU 2200 of FIG.22 may be used. Hereinafter, an example in which a symbol (e.g., theInd_symbol 2250) following the RL-SIG is configured for EHT packetclassification may be described.

1. In the third embodiment, the symbol after the RL-SIG may include asymbol related to the EHT PPDU (or EHT packet). The symbol may be calledvariously. For example, the symbol may be referred to as an indicationsymbol (or a detection symbol). The indication symbol is forillustration, and the symbol may be called otherwise. Hereinafter, forconvenience of description, the symbol may be referred to as anInd_symbol (indication symbol).

2. According to an embodiment, BPSK constellation mapping may be appliedto the Ind_symbol.

3. According to an embodiment, the Ind_symbol may be configured as a bitfor information related to the packet and/or early indicationinformation. According to an embodiment, the Ind_symbol may beconfigured with a sequence for indicating the information related to thepacket and/or the early indication information. That is, the Ind_symbolmay include the information related to the packet and the earlyindication information. For example, the Ind_symbol may be configuredwith bit information including the information related to the packet andthe early indication information. In another example, the Ind_symbol maybe configured with a sequence including the information related to thepacket and the early indication information.

3-A. For example, an information bit included in the Ind_symbol (or onesymbol) may include various types of information. An example ofinformation included in the information bit may be described below.

3-A-i) Information related to packet indication

According to an embodiment, information related to packet indication maybe set to two to four bits.

3-A-i-a) For an advanced system after the EHT standard (i.e., for futureextension), the information related to the packet indication may be setto up to four bits. A STA transmitting the EHT PPDU (hereinafter,transmitting STA) may transmit the information related to the packet (orPPDU) using bits (two to four bits) including the information related tothe packet indication.

3-Aib) Transmitting the information related to the packet indicationfirst enables a STA receiving the EHT packet (or EHT PPDU) (hereinafter,receiving STA) to quickly determine which packet the received packet (orPPDU) is. Accordingly, it is possible to reduce power consumption of thereceiving STA.

3-A-ii) Information related to BSS color

3-A-ii-a) The receiving STA may determine whether the received packet isa BSS packet or an OBSS packet.

3-A-ii-b) Information related to a BSS color may be configured asinformation of 6 to 11 bits.

3-A-ii-c) To enable the receiving STA to quickly conduct determinationof an OBSS, the information related to the BSS color may be transmittedbefore the information related to the packet indication. Accordingly,when the information bit is configured, the information related to theBSS color may be positioned at the forefront.

3-A-iii) Information related to bandwidth (BW)

3-A-iii-a) To signaling overhead in using a wide bandwidth considered ina future extension and the EHT standard, the Ind_symbol (or informationbit) may include information related to the wide bandwidth.

3-A-iii-b) The information related to the bandwidth (BW) information maybe configured as information of one to two bits.

For example, the information related to the bandwidth (BW) may beconfigured as one-bit information. When the one-bit information is setto a first value (e.g., “0”), the one-bit information may refer to abandwidth less than (or less than or equal to) 160 MHz. When the one-bitinformation is set to a second value (e.g., “1”), the one-bitinformation may refer to a bandwidth equal to or more than (or morethan) 160 MHz.

In another example, the information related to the bandwidth (BW) may beconfigured as two-bit information. When the two-bit information is setto a first value (e.g., “00”), the 2-bit information may refer to abandwidth of 160 MHz. When the two-bit information is set to a secondvalue (e.g., “01”), the 2-bit information may refer to a bandwidth of240 MHz. When the two-bit information is set to a third value (e.g.,“10”), the 2-bit information may refer to a bandwidth of 320 MHz. Afourth value (e.g., “11”) may be set as reserved.

3-A-iii) Information related to CRC and/or information related to paritybit

Information related to a CRC may be configured as four-bit information.Information related to a parity bit may be configured as one-bitinformation.

3-A-iii-a) The information bit may include a CRC or a parity bit, suchas the L-SIG, for error detection on the information bit.

3-A-iii-b) The Ind_symbol (or information bit) may include a tail bit.The tail bit may be configured as six-bit information.

3-B. The Ind_symbol may include one OFDM symbol. The Ind_symbol may bepositioned after the RL-SIG and before an EHT-SIG in the EHT frame (orEHT PPDU). That is, the Ind_symbol may be contiguous to the RL-SIG. TheEHT-SIG may be contiguous to the Ind_symbol.

4. As described in the foregoing examples, it is possible to reducefalse detection by legacy STAs by transmitting the Ind_symbol includingthe information related to the packet indication in the EHT frame.

4-A. When receiving the EHT PPDU, an 11n STA and an 11ac STA may receivetwo OFDM symbols modulated with BPSK after the L-SIG. The 11n STA andthe 11ac STA may perform packet classification based on the two OFDMsymbols.

For example, according to 802.11n, both of two symbols following anL-SIG in an 11n PPDU are set to QBPSK. Therefore, the 11n STA may notdetermine the EHT PPDU as an 11n PPDU when performing a constellationmapping check.

For example, according to 802.11ac, two symbols following an L-SIG in an11ac PPDU are set as BPSK and QBPSK. Therefore, the 11ac STA may notdetermine the EHT PPDU as an 11ac PPDU when performing a constellationmapping check.

Accordingly, it is possible to reduce false detection by the 11n STA andthe 11ac STA.

4-B. In the 11ax STA, the EHT PPDU passes a repetition check but doesnot pass a content check. Specifically, in the EHT PPDU, the lengthfield is set to a value divisible by 3, and thus the 11ax STA may notdetermine the EHT PPDU as an flax PPDU. Accordingly, it is possible toreduce false alarms by the 11ax STA.

4-C. The EHT STA may determine whether the received PPDU is an flax PPDUthrough a repetition check and a content check in the same manner as the11ax STA. In addition, the EHT STA may determine whether the receivedPPDU is an EHT PPDU using the information related to the packetindication included in the Ind_symbol (indication symbol) following theRL-SIG.

5. For range extension or reliable sensitivity, the Ind_symbol may beconfigured with a signal that is repeated in terms of time or frequencywithin one symbol.

5-A. Example in which the Ind_symbol is configured with a signalrepeated in terms of time

5-A-i) To configure the symbol with the same repeated signal within onesymbol, the transmitting STA may transmit data through two-carrier (orsubcarrier) spacing in terms of frequency.

5-A-ii) In this case, the information bit transmitted through theInd_symbol may include a packet indication bit, a CRC, and a tail bitfor the EHT PPDU (or EHT frame).

5-B. Example in which the Ind_symbol is configured with a signalrepeated in terms of frequency

5-B-i) The Ind_symbol may be configured by applying dual carriermodulation applied to 802.11ax standard.

5-B-ii) In this case, the information bit transmitted through theInd_symbol may include a packet indication bit, a CRC and a tail bit forthe EHT PPDU (or EHT frame).

5-C. As described in the foregoing examples, the Ind_symbol followingthe RL-SIG may be configured with a symbol including a signal repeatedin terms of time or frequency, thereby increasing reliability of the EHTPPDU.

6. Unlike the foregoing examples, the Ind_symbol may be configured witha signature sequence for packet indication.

6-A. The signature sequence may include a time sequence or a frequencysequence.

6-A-i) The transmitting STA may indicate information related to thepacket using the signature sequence. That is, the signature sequence mayinclude information related to the packet.

6-A-ii) The signature sequence may be configured with sequences betweenthe Euclidean distance is long in order to reduce sequence detectionerrors. Here, the signature sequence may be configured using a sequencehaving a good correlation characteristic (e.g., a PN-sequence, an MLsequence, or an orthogonal sequence).

6-B. Since the Ind_symbol is configured using the signature sequence,the receiving STA may perform correlation detection and/or sequencedetection through decoding on a symbol following the RL-SIG in areceived signal. The receiving STA may determine whether the receivedsignal is an EHT PPDU based on the correlation detection and/or thesequence detection.

Fourth Embodiment

According to a fourth embodiment, an EHT-SIG symbol may be transmittedafter an RL-SIG in an EHT PPDU.

FIG. 23 illustrates another format of an EHT PPDU.

Referring to FIG. 23 , an EHT PPDU 2300 may include an L-STF 2310, anL-LTF 2320, an L-SIG 2330, an RL-SIG 2340, an EHT-SIG 2350, an EHT-SIG2360, an EHT-STF 2370, an EHT-LTF 2380, and/or an EHT-data 2390. The EHTPPDU 2300 may be related to the PPDU illustrated in FIG. 18 . TheEHT-SIG 2350 may be related to the U-SIG illustrated in FIG. 18 .

According to an embodiment, the EHT-SIG 2350 may be positionedimmediately after the RL-SIG 2340. That is, the EHT-SIG 2350 may becontiguous to the RL-SIG 2340. Symbols of the EHT-SIGs 2350 and 2360 mayinclude packet indication information (or information related to packetindication). According to an embodiment, the number of symbols of theEHT-SIGs 2350 and 2360 is for illustration, and the number of symbols ofthe EHT-SIGs 2350 and 2360 may be variously set. For example, the numberof symbols of the EHT-SIGs 2350 and 2360 may be three or more.Specifically, the EHT-SIG 2350 may be set to two symbols. In addition,the EHT-SIG 2360 may be set to at least one symbol.

For the fourth embodiment, a frame structure of the EHT PPDU 2300 ofFIG. 23 may be used. Hereinafter, field information of the EHT PPDUaccording to the fourth embodiment may be described. The EHT-SIG to bedescribed below may refer to at least one of the EHT-SIG 2350 and/or theEHT-SIG 2360 of FIG. 23 .

1. In the EHT PPDU (or EHT frame), the value of a length field of theL-SIG and RL-SIG may be set to a value divisible by 3. That is, thevalue of the length field of the L-SIG and the RL-SIG may be set suchthat a result of applying “modulo 3” is 0.

2. The EHT-SIG may be configured by including the information related tothe packet indication. The information related to the packet indicationmay be used for early detection in a receiving STA. One symbol of theEHT-SIG may include the information related to the packet indication forthe early detection.

2-A. For example, an EHT SIGA included in the EHT-SIG may include“EHT-SIGA-early” configured with one OFDM symbol including the packetindication and “EHT-SIGA” including common information. In the EHT-SIG(or EHT SIGA), an information bit may be configured so that theinformation related to the packet indication may be positioned at theforefront.

2-B. The EHT-SIGA-early may be individually encoded and configured. TheEHT-SIGA-early may be configured to include CRC/parity+tail bits. Forexample, the EHT-SIGA-early may include a CRC bit and a tail bit. Inanother example, the EHT-SIGA-early may include a parity bit and a tailbit.

2-C. The EHT-SIGA-early (or EHT-SIGA-early symbol) may be configuredusing the information included in the Ind_symbol in the third embodimentdescribed above.

2-D. The EHT-SIGA-early may be configured by applying example 5 of thethird embodiment described above. For example, the EHT-SIGA-early may beconfigured such that a signal is repeated in time or frequency forrobust transmission or range extension.

According to the fourth embodiment, the EHT-SIGA-early transmittedimmediately after the RL-SIG may be transmitted after being modulatedthrough BPSK. Therefore, it is possible to reduce the probability offalse detection by a legacy STA (e.g., 11n STA or 11ac STA). A data bitof the EHT-SIGA-early may be configured differently from the HE-SIGAfield. For example, the data bit of the EHT-SIGA-early may be designedto have a long Euclidean distance from the HE-SIGA field. Therefore,when the 11ax STA decodes a symbol of the EHT-SIGA-early, it is possibleto avoid an error of determining the EHT-SIGA-early as the HE-SIGA. Thatis, it is possible to reduce false detection by the 11ax STA.

Fifth Embodiment

Unlike the foregoing embodiments, in embodiments other than the firstembodiment, the length field of the L-SIG may be set to a value suchthat the remainder obtained by dividing the length field by 3 is 1 or 2as in the 802.11ax standard. Here, an 11ax STA and an EHT STA mayperform packet detection through the following embodiment. Hereinafter,an example in which the remainder obtained by dividing the value of thelength field of the L-SIG by 3 is set to 1 or 2 in the second to fourthembodiments will be described.

1. When the second embodiment is applied

According to the second embodiment, the RL-SIG may not have a structurein which the L-SIG is repeated. Therefore, the legacy STA and/or the EHTSTA may distinguish a packet using a repetition check and a bit patternor polarization of the RL-SIG.

1-A. For example, when receiving the EHT PPDU (EHT packet), the 11ax STAmay perform a repetition check. The 11ax STA may determine that theL-SIG and the RL-SIG are not repeated based on the repetition check andmay not decode the EHT PPDU.

1-B. For example, when receiving the EHT PPDU (EHT packet), the EHT STAmay perform a repetition check using a sequence or polarization appliedto the RL-SIG. When the L-SIG is repeated in the RL-SIG, the EHT STA maydetermine the EHT PPDU as an EHT PPDU.

2. When the third and fourth embodiments are applied

According to the third embodiment and/or the fourth embodiment, whenreceiving the EHT PPDU (or EHT packet), the 11ax STA may perform arepetition check and a content check. The 11ax STA may determine thereceived EHT PPDU as an 11ax PPDU. Accordingly, the 11ax STA may decodethe EHT PPDU. The 11ax STA may determine a field after the RL-SIG as anHE-SIGA and may decode the field. However, in the EHT PPDU, a symbolfollowing the RL-SIG is configured differently from the HE-SIGA. In the11ax STA, the EHT PPDU may not pass a CRC check. Therefore, afterfailing to decode the HE-SIGA, the 11ax STA may set a NAV as long as thelength (or time) of the EHT PPDU obtained/identified through the lengthfield.

2-A. The EHT STA may perform a repetition check and a contention checkin the same manner as the 11ax STA. The EHT STA may decode one symboland may identify/obtain information related to packet indication. TheEHT STA may determine whether a received signal is an EHT PPDU based onthe information related to the packet indication.

2-B. Since both the 11ax STA and the EHT STA determine a packet (packetformat) based on packet classification and data decoding according to802.11ax, detection may take a longer time. In addition, unnecessarypower consumption may occur.

FIG. 24 is a flowchart illustrating an operation of a transmitting STA.

Referring to FIG. 24 , in S2410, the transmitting STA (e.g., STAs 110and 120) may generate an EHT PPDU. According to an embodiment, the EHTPPDU may include various fields. For example, the EHT PPDU may includean L-SIG field and a RL-SIG field. In one example, the RL-SIG field maybe contiguous to the L-SIG field.

According to an embodiment, the RL-SIG field may be configured such thatthe L-SIG field is repeated. For example, the RL-SIG field includes thesame information as the L-SIG field and may be modulated by the samemethod as the L-SIG field. BPSK modulation may be applied to the L-SIGfield and the RL-SIG field.

In another example, the RL-SIG field may include the same information asthe L-SIG field but may be configured differently therefrom. In anexample, the RL-SIG field may be configured with complementary bits ofbits forming the L-SIG field. In another example, the RL-SIG field maybe configured with the result of an XOR operation of the bits formingthe L-SIG field and a specific bit or sequence.

According to an embodiment, the transmitting STA may set the value of alength field of the L-SIG field based on the transmission time of theEHT PPDU. For example, the transmitting STA may set the value of thelength field based on Equation 13 described above. For example, theresult of applying “modulo 3” to the value of the length field of theL-SIG field may be set to “0”.

According to an embodiment, the EHT PPDU may include a universal signalfield. For example, the universal signal field may include a U-SIG. Forexample, the universal signal field may include control informationrelated to the EHT PPDU.

In an example, the universal signal field may include informationrelated to the type of the EHT PPDU. The universal signal field mayinclude information indicating that the EHT PPDU is a PPDU based on theEHT standard. The information related to the type of the EHT PPDU may beconfigured as three-bit information.

In another example, the universal signal field may include informationrelated to a basic service set (BSS) color or information related to abandwidth.

In S2420, the transmitting STA may transmit the EHT PPDU. According toan embodiment, the transmitting STA may transmit the EHT PPDU to areceiving STA.

FIG. 25 is a flowchart illustrating an operation of a receiving STA.

Referring to FIG. 25 , in S2510, the receiving STA (e.g., STAs 110 and120) may receive a PPDU. According to an embodiment, the PPDU mayinclude an L-SIG field.

In S2520, the receiving STA may determine the type of the PPDU based onwhether the L-SIG field is repeated and a “modulo 3 operation” withrespect to the value of a length field.

According to an embodiment, the type of the PPDU may include a legacytype, an HE type, and an EHT type. The PPDU of the legacy type may be alegacy PPDU. The PPDU of the HE type may be an HE PPDU. The PPDU of theEHT type may be an EHT PPDU.

According to an embodiment, the PPDU of the EHT type may include anRL-SIG field in which the L-SIG field is repeated. The RL-SIG field maybe contiguous to the L-SIG. The RL-SIG field may include the sameinformation field as the L-SIG field.

According to an embodiment, the receiving STA may determine/detectwhether the L-SIG field is repeated. The receiving STA may determine thetype of the PPDU based on whether the L-SIG field is repeated. Forexample, to determine whether the L-SIG field is repeated, the receivingSTA may determine whether the L-SIG field and the RL-SIG field are thesame.

For example, the L-SIG field may not be repeated in the received PPDU.When the L-SIG field is not repeated, the PPDU received by the receivingSTA may be determined as a legacy-type PPDU (legacy PPDU).

For example, the L-SIG field may be repeated in the received PPDU. Thatis, the L-SIG field and the RL-SIG field may be identically set. Whenthe L-SIG field is repeated, the PPDU received by the receiving STA maybe determined as an HE-type PPDU (HE PPDU) or an EHT-type PPDU (EHTPPDU).

In an example, the RL-SIG field may include the same information as theL-SIG field and may be modulated by the same method as the L-SIG field.BPSK modulation may be applied to the L-SIG field and the RL-SIG field.

In another example, the RL-SIG field may include the same information asthe L-SIG field but may be configured differently therefrom. In anexample, the RL-SIG field may be configured with complementary bits ofbits forming the L-SIG field. In another example, the RL-SIG field maybe configured with the result of an XOR operation of the bits formingthe L-SIG field and a specific bit or sequence.

The legacy-type PPDU (legacy PPDU) may refer to PPDUs of variousstandards. For example, the legacy PPDU may include a non-highthroughput (non-HT) PPDU, a high throughput (HT) PPDU, or a very highthroughput (VHT) PPDU.

According to an embodiment, the receiving STA may determine the type ofthe PPDU based on the “modulo 3 operation” with respect to the value ofthe length field. For example, the value of the length field may be setbased on the transmission time of the PPDU. In one example, the value ofthe length field may be set based on Equation 13 described above.

For example, the PPDU may be determined as an HE PPDU in which theresult of the “modulo 3 operation” has a value of “1” or “2”. That is,the type of the PPDU may be determined as the HE type of a PPDU in whichthe result of the “modulo 3 operation” is “1” or

In another example, the PPDU may be determined as an EHT PPDU in whichthe result of the “modulo 3 operation” is “0”. That is, the type of thePPDU may be determined as the HE type for a PPDU in which the result ofthe “modulo 3 operation” is “0”.

According to an embodiment, the receiving STA may perform the “modulo 3operation” with respect to the value of the length field. For example,the receiving STA may identify that the result of the operation is “0”.The receiving STA may identify that the received PPDU is an EHT PPDUbased on the result of the “modulo 3” operation. That is, the receivingSTA may identify that the type of the received PPDU is the EHT typebased on the result of the “modulo 3” operation. In another example, thereceiving STA may identify that the result of the operation is “1” or“2”. The receiving STA may identify that the received PPDU is an HE PPDUbased on the result of the “modulo 3 operation”. That is, the receivingSTA may identify that the type of the received PPDU is the HE type basedon the result of the “modulo 3” operation.

According to an embodiment, the received PPDU may include a universalsignal field. For example, the EHT PPDU may include the universal signalfield. For example, the universal signal field may include a U-SIG. Forexample, the universal signal field may include control informationrelated to the PPDU.

In an example, the universal signal field may include informationrelated to the type of the PPDU. The universal signal field may includeinformation indicating that the PPDU is a PPDU based on the EHTstandard. The information related to the type of the PPDU may beconfigured as three-bit information.

In another example, the universal signal field may include informationrelated to a basic service set (BSS) color or information related to abandwidth.

In S2530, the receiving STA may decode the PPDU. According to anembodiment, the receiving STA may determine the received PPDU as an EHTPPDU. That is, the receiving STA may determine the type of the receivedPPDU as the EHT type. The receiving STA may decode the received PPDUbased on the EHT type.

The foregoing technical features of the present specification may beapplied to various devices and methods. For example, the foregoingtechnical features of the present specification may beperformed/supported through the apparatus of FIG. 1 and/or FIG. 19 . Forexample, the foregoing technical features of the present specificationmay be applied to only part of FIG. 1 and/or FIG. 19 . For example, theforegoing technical features of the present specification may beimplemented based on the processing chips 114 and 124 of FIG. 1 , may beimplemented based on the processors 111 and 121 and the memories 112 and122 of FIG. 1 , or may be implemented based on the processor 610 and thememory 620 of FIG. 19 . For example, an apparatus of the presentspecification may be configured to: receive a physical protocol dataunit (PPDU) including an L-SIG field; determine the type of the PPDUbased on whether the L-SIG field is repeated and a “modulo 3 operation”with respect to the value of a length field, the PPDU being determinedas an extreme high throughput (EHT) PPDU in which the result of the“modulo 3 operation” is “0”, and the PPDU of an EHT type including anRL-SIG field in which the L-SIG field is repeated; and decode the PPDU.

The technical features of the present specification may be implementedbased on a computer-readable medium (CRM). For example, the CRM proposedaccording to the present specification may store instructions to performoperations including: receiving a physical protocol data unit (PPDU)including an L-SIG field and an RL-SIG field, the type of the PPDU beingdetermined based on whether the L-SIG field is repeated and a “modulo 3operation” with respect to the value of a length field, the PPDU beingdetermined as an extreme high throughput (EHT) PPDU in which the resultof the “modulo 3 operation” is “0”, and the PPDU of an EHT typeincluding the RL-SIG field in which the L-SIG field is repeated; anddecoding the PPDU. The instructions stored in the CRM of the presentspecification may be executed by at least one processor. The least oneprocessor related to the CRM of the present specification may be theprocessors 111 and 121 or the processing chips 114 and 124 of FIG. 1 ormay be the processor 610 of FIG. 19 . The CRM of the presentspecification may be the memories 112 and 122 of FIG. 1 , may be thememory 620 of FIG. 19 , or may be a separate external memory/storagemedium/disk.

The foregoing technical features of this specification are applicable tovarious applications or business models. For example, the foregoingtechnical features may be applied for wireless communication of a devicesupporting artificial intelligence (AI).

Artificial intelligence refers to a field of study on artificialintelligence or methodologies for creating artificial intelligence, andmachine learning refers to a field of study on methodologies fordefining and solving various issues in the area of artificialintelligence. Machine learning is also defined as an algorithm forimproving the performance of an operation through steady experiences ofthe operation.

An artificial neural network (ANN) is a model used in machine learningand may refer to an overall problem-solving model that includesartificial neurons (nodes) forming a network by combining synapses. Theartificial neural network may be defined by a pattern of connectionbetween neurons of different layers, a learning process of updating amodel parameter, and an activation function generating an output value.

The artificial neural network may include an input layer, an outputlayer, and optionally one or more hidden layers. Each layer includes oneor more neurons, and the artificial neural network may include synapsesthat connect neurons. In the artificial neural network, each neuron mayoutput a function value of an activation function of input signals inputthrough a synapse, weights, and deviations.

A model parameter refers to a parameter determined through learning andincludes a weight of synapse connection and a deviation of a neuron. Ahyper-parameter refers to a parameter to be set before learning in amachine learning algorithm and includes a learning rate, the number ofiterations, a mini-batch size, and an initialization function.

Learning an artificial neural network may be intended to determine amodel parameter for minimizing a loss function. The loss function may beused as an index for determining an optimal model parameter in a processof learning the artificial neural network.

Machine learning may be classified into supervised learning,unsupervised learning, and reinforcement learning.

Supervised learning refers to a method of training an artificial neuralnetwork with a label given for training data, wherein the label mayindicate a correct answer (or result value) that the artificial neuralnetwork needs to infer when the training data is input to the artificialneural network. Unsupervised learning may refer to a method of trainingan artificial neural network without a label given for training data.Reinforcement learning may refer to a training method for training anagent defined in an environment to choose an action or a sequence ofactions to maximize a cumulative reward in each state.

Machine learning implemented with a deep neural network (DNN) includinga plurality of hidden layers among artificial neural networks isreferred to as deep learning, and deep learning is part of machinelearning. Hereinafter, machine learning is construed as including deeplearning.

The foregoing technical features may be applied to wirelesscommunication of a robot.

Robots may refer to machinery that automatically process or operate agiven task with own ability thereof. In particular, a robot having afunction of recognizing an environment and autonomously making ajudgment to perform an operation may be referred to as an intelligentrobot.

Robots may be classified into industrial, medical, household, militaryrobots and the like according uses or fields. A robot may include anactuator or a driver including a motor to perform various physicaloperations, such as moving a robot joint. In addition, a movable robotmay include a wheel, a brake, a propeller, and the like in a driver torun on the ground or fly in the air through the driver.

The foregoing technical features may be applied to a device supportingextended reality.

Extended reality collectively refers to virtual reality (VR), augmentedreality (AR), and mixed reality (MR). VR technology is a computergraphic technology of providing a real-world object and background onlyin a CG image, AR technology is a computer graphic technology ofproviding a virtual CG image on a real object image, and MR technologyis a computer graphic technology of providing virtual objects mixed andcombined with the real world.

MR technology is similar to AR technology in that a real object and avirtual object are displayed together. However, a virtual object is usedas a supplement to a real object in AR technology, whereas a virtualobject and a real object are used as equal statuses in MR technology.

XR technology may be applied to a head-mount display (HMD), a head-updisplay (HUD), a mobile phone, a tablet PC, a laptop computer, a desktopcomputer, a TV, digital signage, and the like. A device to which XRtechnology is applied may be referred to as an XR device.

The claims recited in the present specification may be combined in avariety of ways. For example, the technical features of the methodclaims of the present specification may be combined to be implemented asa device, and the technical features of the device claims of the presentspecification may be combined to be implemented by a method. Inaddition, the technical characteristics of the method claim of thepresent specification and the technical characteristics of the deviceclaim may be combined to be implemented as a device, and the technicalcharacteristics of the method claim of the present specification and thetechnical characteristics of the device claim may be combined to beimplemented by a method.

What is claimed is:
 1. A method performed by a station (STA) in awireless local area network system, the method comprising: receiving aphysical protocol data unit (PPDU) comprising a legacy-signal (L-SIG)field; determining whether the PPDU comprises a repeated L-SIG (RL-SIG)field which is a repeat of the L-SIG field, wherein the RL-SIG iscontiguous to the L-SIG field; and after determining that the PPDUcomprises the RL-SIG field, determining whether a length field includedin the L-SIG field is set to a value satisfying a condition that aremainder is zero when a value of the length field is divided by three(3), wherein the remainder is used to differentiate an extreme highthroughput (EHT) PPDU from a high efficiency (HE) PPDU, wherein the PPDUis determined as the EHT PPDU based on the remainder having a value ofzero (0), and the PPDU is determined as the HE PPDU based on theremainder having a non-zero value.
 2. The method of claim 1, furthercomprising: after determining the length field is set to the valuesatisfying the condition, evaluating a physical version field comprisedin a universal signal (U-SIG) field of the PPDU, wherein the physicalversion field has a length of three (3) bits.
 3. The method of claim 2,wherein the universal signal (U-SIG) field further comprises informationrelated to a basic service set (BSS) color of the PPDU and/orinformation related to a bandwidth of the PPDU.
 4. The method of claim1, wherein binary phase shift keying (BPSK) modulation is applied to theL-SIG field and the RL-SIG field.
 5. The method of claim 1, wherein thevalue of the length field is related to a transmission time of the PPDU.6. The method of claim 1, wherein the STA is an access point (AP) STA ora non-AP STA.
 7. A station (STA) in wireless local area network (WLAN)system, the receiving STA comprising: a transceiver to transmit andreceive a wireless signal; and a processor coupled to the transceiver,wherein the processor is adapted to: receive a physical protocol dataunit (PPDU) comprising a legacy-signal (L-SIG) field; determine whetherthe PPDU comprises a repeated L-SIG (RL-SIG) field which is a repeat ofthe L-SIG field, wherein the RL-SIG is contiguous to the L-SIG field;and after determining that the PPDU comprises the RL-SIG field,determine whether a length field included in the L-SIG field is set to avalue satisfying a condition that a remainder is zero when a value ofthe length field is divided by three (3), wherein the remainder is usedto differentiate an extreme high throughput (EHT) PPDU from a highefficiency (HE) PPDU, wherein the PPDU is determined as the EHT PPDUbased on the remainder having a value of zero (0), and the PPDU isdetermined as the HE PPDU based on the remainder having a non-zerovalue.
 8. The STA of claim 7, wherein the processor is further adaptedto: after determining the length field is set to the value satisfyingthe condition, evaluate a physical version field comprised in auniversal signal (U-SIG) field of the PPDU, wherein the physical versionfield has a length of three (3) bits.
 9. The STA of claim 8, wherein theuniversal signal (U-SIG) field further comprises information related toa basic service set (BSS) color of the PPDU and/or information relatedto a bandwidth of the PPDU.
 10. The STA of claim 7, wherein binary phaseshift keying (BPSK) modulation is applied to the L-SIG field and theRL-SIG field.
 11. The STA of claim 7, wherein the value of the lengthfield is related to a transmission time of the PPDU.
 12. The STA ofclaim 7, wherein the STA is an access point (AP) STA or a non-AP STA.